diff --git "a/Botany/botany_for_beginners_1899.md" "b/Botany/botany_for_beginners_1899.md" new file mode 100644--- /dev/null +++ "b/Botany/botany_for_beginners_1899.md" @@ -0,0 +1,10083 @@ +BOTANY +FOR BEGINNERS + +ERNEST EVANS + +PRESENTED TO THE UNIVERSITY OF TORONTO BY The G. P. & A. R. Clark Company + +Examination copies of the accompanying Book have just reached us from the Publishers. We have pleasure in sending one to your address. + +THE COPP, CLARK COMPANY, LIMITED +9 Front St. West, TORONTO + +Image of a blank piece of paper with a small rectangular cutout on the left side. + +A blank page with a small dark spot in the center. + +A blank, light brown paper with some small, dark spots scattered across its surface. + +BOTANY FOR BEGINNERS + +BOTANY FOR BEGINNERS + +
+ +Bot. gen. + +BOTANY +FOR BEGINNERS + +BY +ERNEST EVANS +NATURAL SCIENCE MASTERS, MECHANICS' INSTITUTE +AND TECHNICAL SCHOOL, BURNLEY + +A circular stamp with "HISTORICAL SOCIETY" around the edge and "OF THE" at the top. + +London +MACMILLAN AND CO., LIMITED +NEW YORK : THE MACMILLAN COMPANY +1899 + +All rights reserved + +47 64 16/1/00 + +RICHARD CLAY AND SONS, LIMITED, +LONDON AND BENGAL. + +PREFACE + +It is now generally accepted by educationists that experi- +mental work is an essential part of instruction in any branch of +physical or natural science. Too much importance cannot be +attached to knowledge gained direct from Nature; and it is +essential that the student should have an opportunity of pub- +licly examining bodies designed to test the student's own obser- +vations and experience. As an instance of this, it is worth +mentioning that the examination papers prescribed by the +Department of Science and Art, the examiners remark: +"The examination will be especially directed towards ascen- +taining the amount and character of the practically acquired +knowledge of the candidate." + +To provide students with a means of obtaining such knowl- +edge, this little work has been prepared in the spirit of the +"Observations on the Structure and Development of Plants" +of plants. The attempt is often made to study Botany without +the practical examination of plants, and it has produced on the +whole a very unsatisfactory result. This is the result of the old method of teaching Botany by means of ideals or definitions; the new method is to examine +the plants from as many points of view as possible, and to draw +conclusions from them. In this way, when once the subject was +the subject becomes one of living interest, instead of being merely a collection of technical names and terms. It is with +this object in view that this little book has been prepared in the +study of plants a book which shall be a guide and companion, +during a first course that the present volume has been prepared. + +A page from a book about botany. + +vi +PREFACE + +Though the book has been primarily designed to cover the syllabus of the Department of Science and Art, it is by no means a "cram-book" for that particular examination, and a thorough knowledge of its contents will not only lay the foundation for further work in the subject, but also enable the student to pass examination in Botany with distinction. The book should also be useful to teachers in elementary schools, in assisting them to prepare object lessons with plants for the instruction of their pupils. + +Teachers are recommended to see that the students perform the experiments, and keep a complete record of the results obtained. Many of the plants required can be grown at home, and easily be obtained; the others can be grown in the school grounds. A small collection of fruits, seeds, dried and mounted plants, etc., may be purchased from any botanical dealer. + +It is hoped that the introduction into this book of a series of carefully graded experiments with simple apparatus will prove useful to many students and teachers, and will be the means of making botany more interesting than it has been in the past. + +Many of the illustrations have been prepared, after careful consideration, by Mr. W. E. Holt, to whose skill I am much indebted. Figures 128 to 131 have been drawn by my former student, Mr. H. Wright, A.R.C.S. The figures marked S. have been taken from "The Text Book of Botany," placed at my disposal from Struttman's Text Book of Botany. The questions at the ends of the chapters will serve to test whether students have clear ideas on the subjects dealt with. Those who have passed examinations in Botany, Zoology, and Art Department's examinations; and T. signifies Training College questions. + +In conclusion, I desire to acknowledge my indebtedness to Prof. G. C. Gregory and Mr. A. T. Simmons, B.Sc., for many valuable suggestions and much help during the preparation of the manuscript, and the passage of the work through the press. + +ERNEST EVANS. + +MECHANICS' INSTITUTE AND TECHNICAL +SCHOOLS, BURNLEY, + +A page from a book titled "PREFACE" discussing botany education. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
CONTENTS
CHAPTER IPAGE 1
INTRODUCTION
CHAPTER II
MORPHOLOGY--STUDY OF THE BODY OF A PLANT$
CHAPTER III
ANATOMY--STUDY OF THE SHOOT16
CHAPTER IV
THE STUDY OF THE SHOOT (continued)34
CHAPTER V
ANATOMY--STUDY OF ROOTS51
CHAPTER VI
SECTIONS, HOW TO PREPARE AND EXAMINE THEM61
CHAPTER VII
THE HISTOLOGY OF THE CELLS74
CHAPTER VIII
THE HISTOLOGY OF THE TISSUES93
CHAPTER IX
THE HISTOLOGY OF THE SHOOT AND ROOT103
+ +viii CONTENTS + +CHAPTER X +THE PHYSIOLOGY OF NUTRITION 168 +CHAPTER XI +THE ABSORPTION AND MOVEMENT OF WATER IN THE PLANT 137 +CHAPTER XII +THE PHYSIOLOGY OF GROWTH AND MOVEMENT 152 +CHAPTER XIII +FLOWER AND INFLORESCENCES 164 +CHAPTER XIV +THE TERMS USED IN DISCRIMINATING THE FLOWER 178 +CHAPTER XV +THE DEVELOPMENT AND MORPHOLOGY OF THE FLOWER 193 +CHAPTER XVI +POLLINATION AND FERTILISATION 206 +CHAPTER XVII +THE MORPHOLOGY OF SEED AND FRUITS, AND THEIR DISTRIBUTION 222 +CHAPTER XVIII +THE PHYSIOLOGY OF REPRODUCTION 237 +CHAPTER XIX +THE CLASSIFICATION OF PLANTS 242 +CHAPTER XX +CLASSIFICATION OF PLANTS (Continued) 265 +PLANT DESCRIPTION 283 +INDEX 287 + +BOTANY FOR BEGINNERS + +CHAPTER I +INTRODUCTION + +Definition.—The branch of science the object of which is the study of the plant, from as many different points of view as possible, is termed Botany. All its laws can be proved by observation and experiment, and it is consequently known as one of the sciences. But, although we may know what a plant is, it is impossible to clearly define what is meant by a plant, because the higher plants differ in many respects from the lower, and so many exceptions to any rule we may state present themselves. The term "plant" has been used by some authors to divide all forms of life into animals and plants, but we find we cannot, with the knowledge of to-day, draw a clear boundary line between them. For example, there is no clear difference between an oak tree and a horse, but when the lower forms of life are examined no clear division can be drawn between animal and plants. All living things are built up of the same kind of material, and they have the same functions. This has been called the physical basis of life, because life is never found apart from it. There appears to be no difference between the lower and higher forms of life, except that the latter are plants. In fact, what we speak of as the tree of life is forked, the animals being found on one side and the plants on the other. + +E B + +2 +BOTANY FOR BEGINNERS +CHAP. + +and both of them spring from the lowly forms which are found at the base. +Higher Animals. +E.g. Horns. +Higher Plants. +E.g. Oak. +Lower forms of life + +Living and Non-living Bodies.—It will be well to at once consider the question of the differences between living and non-living bodies ; and here a fairly clear boundary line can be drawn. +1. Living bodies are characterised by the nature of their external form. Their shape is definite, and bounded more or less by curved surfaces. Non-living bodies are either amorphous, that is, without definite shape, or crystalline, that is bodies with a definite shape. Crystals are formed on flat surfaces meeting in sharp edges. +2. Living bodies are able to reproduce their kind, but non-living bodies have no power of reproduction. +3. Living bodies take in food, which supplies material for growth, the growth taking place from the inside. Non-living bodies do not grow, but they may be made to grow if placed under suitable conditions. The growth or increase in size of a crystal always takes place on the outside, not internally. +The Object of the Plant.—Plants, then, are living things, and we must learn to treat them as such. Plants produce seeds, which enable them to multiply themselves like man, but so that the continuity of the particular race of plants can be kept up. The living, working, struggling plant has only + +INTRODUCTION 3 + +One object in life, that is, to reproduce its kind... All the parts of the plant are designed with this object in view; the shape, colour, and perfume of the flowers, and all the various contriv- + + +A group of mineral specimens, including a crystal, a flint, and a rock. + + + +A group of vegetable specimens, including a leaf, a flower, and a root. + + + +A bird and a fish. + + + +A human figure. + + +Fig. 1.--Illustration of the difference in the external forms of the mineral, +ancres with which plants are endowed, are to be regarded as means towards accomplishing this reproduction. + +Scope of Our Lessons.--We shall have to consider the plant from the following points of view:--(i) Morphology, or the science of form and structure; (ii) Physiology, or the science of function; (iii) Classification, or the science of relations. + +B + +4 +BOTANY FOR BEGINNERS +CHAP. + +**Morphology.--That portion of the study of living things which deals with the shape and structure of the various organs of plants or animals is termed morphology. Morphology is divided into two parts, **anatomy**, which means, as far as our lessons are concerned, the arrangement of the parts of a plant or animal made out by the aid of a knife, the naked eye, or by the aid of a microscope ; and **histology**, or the minute structure of the various cells. These two branches of the use of the compound microscope are for this course the only ones to be studied. + +**Physiology.--This division of botany is concerned with those functions which, taken together, constitute the life of the plant. Just as anatomy deals with the parts of a plant or animal, so physiology deals with what they do. There are several divisions into which physiology can be divided, for example— + +1. The **digestion** of food. This includes all that concerns its food, together with the changes that go on in the food due to the activity of the living substance of the plant, so that the food may become assimilated or become converted into sugar, starch, cellulose, and proteins. + +2. The **Physiology** of Movement, or how plants move. That various movements are performed by plants, such as the closing of flowers, the so-called sleep of leaves, and the changes in the position of stems, such as the twining stems of the hop, and the tendency of some plants to grow upwards. In this physiology tries to answer all questions relating to the causes that produce the various movements of plants, and how these movements are affected by the activity of their tissues. + +3. The **Physiology** of Reproduction, or how plants reproduce their kind. Some plants reproduce by means of bulbs and tubers. This kind of reproduction is termed *vegetative*, because it is produced by vegetative organs, i.e., by organs only portions produced by the vegetative functions of the plant. + +In far the greater number of cases, plants reproduce their kind by means of seeds. This kind of reproduction is termed *sexual*. + +**Classification.--The province of classification is to point out the relations between different groups of plants. Many kinds of classification have been devised, and many of them are known as artificial systems. + +One of the best known is that of Linnaeus, which is based on + +I INTRODUCTION 5 + +the number and arrangement of the parts of the flower. All the various artificial systems have been superseded by that called the Natural System, which is based on the resemblances and differences of plants. The natural system of classification is, however, not complete, because the relationships between different plants have not been fully worked out. + +To make the more obvious divisions of our subject yet more clear to the reader we arrange them in a tabular form, which should be clearly learnt. + +Botany. +Morphology. Classification. Physiology. +Anatomy. Histology. Nutrition. Movement. Reproduction. + +Life-History of a Plant.—Every plant possesses what is termed a life-history, that is, its life has a beginning, it passes through certain stages, old age comes on, and at last it dies. All these stages are connected with each other, and all these make up its life-history. In all the higher plants the life-history com- +mences with the germination of the seed, continues as that of the seedling, when it becomes a young plant, grows up, then flowering takes place, seeds are produced, the parent dies, and the continuity of the race is kept up by the young plant in the next generation. + +Necessity for Practical Work.—Having now given some idea of the scope and aims of botany, and the boundary lines which separate it from other branches of science, to this subject, the importance of practical work must next be insisted on. + +No true knowledge of natural history can be obtained without practical work; and there is no doubt that such work is well adapted to excite interest in natural history. By attention to details, attainments which are likely to prove of value in whatever walk of life the student may afterwards find himself. + +Botany is one of the best subjects with which to commence the study of science, because the necessary materials for + +6 +BOTANY FOR BEGINNERS +CHAP. + +practical work are abundant, and the instruments required in the early stages are easily obtainable. +Full instructions will be found for carrying out the experiments given in the following pages, and if the student will only per- +form them, and carefully make notes of the results obtained, he, +will have no difficulty in thus acquiring a good working +acquaintance with elementary botany. + +SUMMARY. + +Botany concerns itself with the study of plants. It is a concrete science. +Boundary lines can be easily drawn between the higher plants and the higher animals, but the line of demarcation is difficult to define when we come to the lower forms of life. + +Plants and animals are built up of protoplasm. The tree of life is a forted one. + +DIFFERENCE BETWEEN LIVING AND NON-LIVING BODIES. + +Living. +1. Their shape is definite. +2. Can reproduce their kind. +3. Can take in food and grow +instantly. +The one object of the plant is to reproduce its kind. + +Non-Living. +1. Either of no definite shape or crystalline. +2. Cannot reproduce their kind. +3. Cannot take in food and can only grow from the outside. + +SCOPE OF THE SUBJECT. + +Morphology +A. The science of shape and structure. It is divided into Anatomy or struc- +ture, and Physiology or func- +tion, on the use of the com- +mon microscope. +Histology or struc- +ture, seen by means +of a compound +microscope. + +Physiology +B. The science of func- +tion, what an organ +can do. It is divided into +Embryology or nutri- +tion, Physiology of nutri- +ment, Physiology of re- +production. + +Classification +C. The science of rela- +tionships, embracing plant description, and plac- +ing each species in its true position in the natural system. + +7 + +I + +INTRODUCTION + +7 + +QUESTIONS ON CHAPTER I + +(1) Define the term botany. What are the objects of botany? +(2) What is meant by a concrete science? Why is botany placed somewhere between zoology and geology? +(3) Can a clear boundary line be drawn between the higher animals and plants? Is this possible with the lower forms? +(4) Into what divisions can botany be divided? Why is botany divided into the divisions you mention? +(5) What is meant by the natural system of classification. +(6) What is meant by the life-history of a plant? +(7) Why is practical work of such great importance in natural history? + +CHAPTER II + +MORPHOLOGY.—STUDY OF THE BODY OF A PLANT + +Parts of a Plant.—If any ordinary plant, such as a wall-flower or mustard plant, be examined, we find that it consists of certain well defined parts. + +These parts are known as root and shoot; the shoot can be broken into two, stem and leaf. + +The root and stem are continuous, and together form the axis of the plant. The root is called the descending axis, and the stem the ascending axis. It is by means of these two parts a plant is built up. From a morphological point of view, these parts of a plant are termed its members, and they can be classified under three heads: + +1. **Root-structures**.—These are as a general rule found at the base of the plant. They serve to fit it to the soil, and to take in water and mineral salts. The root of the mustard plant may be mentioned as a typical example. + +2. **Stem-structures**.—These may be aerial, as in the stem of the wall-flower, or subterranean, as in the roots of the mustard plant; or they may be found beneath the soil, as in Solomon's Seal, when they are called subterranean stems. In some cases, like the strawberry, they creep along the surface of the ground, when they are called prostrate stems. The stem both leaves and buds are developed as lateral outgrowths. + +3. **Leaf-structures**.—Leaves are, as a general rule, thin, and green or brightly coloured. They are produced by the stem. + +A diagram showing the different parts of a plant: root (descending axis), stem (ascending axis), and leaves. + +CH. II +MORPHOLOGY +9 + +4. Hair-structures.--These may grow from all parts of the plant and may be short, or long and silky. All hair structures agree in being developed from the epidermis or skin-like coverings of the plant. Some hair-structures serve to keep off uninviting substances, others to protect the plant from the sun, horse chestnut, creosote or form a kind of glue to protect the young buds from cold ; while some are used for the purpose of scattering the seed part in scattering the seeds. + +**Organs.--From a physiolog- ical point of view, the main parts of a plant are spoken of as its **organs**. An organ is a structure which has a definite function to perform some special work, e.g., the root is an organ be- cause it fixes the plant to the soil. + +**Extr. 1.** Obtain a nearly full-grown Wallflower plant, and examine it carefully. + +(i) The shoot is erect and branching, with leaves at first hard and woody. The upper part of the stem is green, and the lower part of it is covered with a pale-brown bark. + +(ii) The leaves are leafy and can be divided into stem and leaf-the latter being called the axil. + +(iii) That the stems branch, and the branches rise from the axils, is shown by the presence of leaf-lives. The space between the two branches is called the axil + +(iv) The leaves are arc-shaped, thin, veined, and lance-shaped. + +(v) The leaves are held by their bases being very close to the surface. Pass your finger over them and note what the hairs feel like. + +(vi) The roots are long and slender, and grow down to the point where it joins the stem in its apex. Spreading from the main root will become evident many secondary roots, or root branches, which help to fix the plant to the soil. + +Fig. 2.--Wallflower Plant. +2 + +10 +BOTANY FOR BEGINNERS +CHAP. + +The stock, or any ordinary plant will do for this experiment. +The body of the wallflower is built up of the same members as are found in an oak tree (Fig. 4), a potato, or many other plants. + +The Parts Present in a Seed.—Most flower- +plants produce their flowers from seeds, and at this point it will be well to consider what parts of seeds. The same parts can be found in a seed as have been described in the wallflower, along with other parts which belong to the present plant. + +The Structure of a Bean + +EXPT. 2.—Soak a few scarlet runner beans in water for twenty-four hours, then dry them on +them. Note: + +(i) The bean is kidney-shaped, and along one side is a dark scar—the +hilum—where the seed was attached to its stalk. + +(ii) The small hole near the hilum—the microspore. It can be seen best by wiping the seed and gently squeezing it, when water will ooze out. + +Fig. 3.—Stem and leaf; showing soil. + +Fig. 4.—Oak Tree. + +II MORPHOLOGY + +(III) If the point of a penknife or a pin is inserted opposite to the hilum, the seed-coat can be removed. The seed-coat, or *epidermis*, consists of two layers; the outer is known as the *testa*, and the inner as the *endosperm*. + +(iv) The seed-coats surround a whitish mass, which may fall in pieces; this is called the *radicle*. If the embryo is examined, you will find here all round the side near the hilum, the body of the embryo, called the *radicle*, the axis of which points towards the micropyle. This radicle is surrounded by the middle layer, into two divisions—the *endosperm* or *cotyledons*. + +(vii) Between the cotyledons will be found the *plumule* or young stem, which is continuous with the radicle, and if you use a lens + +A diagram showing different parts of a bean seed. +A. Bean seed. +B. A side view of seed. +C. Showing radicle. +D. Seed coats. +E. Two cotyledons. + +you will be able to see a number of minute leaves growing from the plumule. + +Explain It: Care has to be taken in examining the embryo, it will be noticed that the radicle, plumule, and cotyledons are all joined together to form the body of the embryo. + +We can represent the relations of the parts of the bean seed as follows: + +Bean. +Embyro. +Coverings. + +Radicle. +Cotyledons. +Plumule. +Testa. +Tegmen. + +Structure of a Grain of Wheat. + +Expt.: - Take a few grains of Indian Corn, and soak them in water for half an hour. Then take one grain at a time, cut off the grain keelwhence with a sharp knife, and look at half of it with a hand lens. + +(i) The covering, which is made up of several layers, only two of + +11 + +12 +BOTANY FOR BEGINNERS +CHAP. + +which correspond to the testa and tegmen of the bean. +The inner layer belongs to the fruit, for the endosperm is in reality a seed (p. 19). + +The micropyle is hidden by the coverings of the fruit and cannot be seen, but at one end of the grain a former will be found, which, when the seed is ripe, is filled with a yellowish fluid, the endosperm, which can be distinguished. This is reserve food material for the use of the young plant. + +On the other hand, in the case of the embryo, in contact with the endosperm, a single cotyledon will be found: and on the outside of this an upper portion, the plumule, and a lower portion, the radicle, can be made out. + +The following table will show the relation of the different parts found in the grain of Indian Corn. + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Kernel.Covering.
Embr. y.Endosperm.Spermoderm.Fruit.
Radicle.Cotyledon.Plumule.
+ +Diocletyloides and Monocotyledoones—In both the Bean and Indian Corn seeds, the embryo consists of radicle, plumule and cotyledons, but the number of cotyledons differs. + +The Indian Corn has only one cotyledon, but the Bean possesses two. These two kinds of plants are sometimes referred to as Diocletyloides, and those with only one as Monocotyledoones. The Bean belongs to the former, and the Indian Corn to the latter. + +**Germination of Seeds.—** The early stages of the development of the embryo are spoken of as germination. If the seed is examined during germination, we can clearly see how the various parts which are found in the embryo act during that process. + +EXPT. 4.—Obtain a few M种子st and place them on a piece of clean paper. Cover them with a glass plate and damp warm. Examine the seeds from day to day, and notice— + +(1) That after a short time is passed is the result of moisture and heat. +(2) At once a small swelling appears, which is due to the radicle pushing its way through the micropyle. + +MORPHOLOGY + +(II) In a few days the seed-capsule has grown into the primary or main root, and from it a large number of secondary roots develop. + +Fig. 6.—Pot of Mustard seedlings, showing secondary leaves. +Fig. 7.—Pot of Mustard seedlings, showing secondary leaves. + +Soil +Root Layer + +Fig. 8.—How to pot a plant. + +(III) The plumule grows upwards towards the light and the cotyledons are green. + +Expt. 5.—Take a few of the young Mustard plants used in the last experiment and a plant pot with soil in, and with a petri-dish make a + +A potted plant with several small, green leaves emerging from the soil. +A potted plant with a larger, more mature stem and several secondary leaves growing from it. +A close-up view of the soil and root layer of a potted plant. + +14 +BOTANY FOR BEGINNERS +CHAÉ. + +few holes in the soil. Plant the mustard seedlings, firmly pressing the soil to the roots. Water the soil and plant the seed just as in the case of the corn. Examine every day, and notice that the apex of the stem gives off new leaves, and that these new leaves are very different from the seed-leaves. + +EXPT. 6.--Take some of the seeds of the Indian Corn used in Experiment 5, and plant them in a pot of sand. Notice that-- + +(1) The seedling is the first to appear above the soil, and its tip is surrounded by the cotyledon. +(2) The cotyledon is a leaf plant from the soil ; the primary root or radicle is very short, and from it are produced a very large number of adventitious roots. + +A Mustard seedling showing adventitious roots. +Fig. 9.--A Mustard seedling, showing adventitious roots of a plant. + +Adventitious roots are those roots which are not produced in regular order. Roots are also given off from the plumule just above the cotyledon. The difference between primary, secondary, and adventitious roots is well seen in the mustard and in the Indian corn. In the mustard, the primary root is a continu- ation of the radicle ; the secondary roots grow from the radicle, in regular order ; but adventitious roots are produced from the stem, or some part of the plant other than the primary root. + +Roots of a plant with several adventitious roots growing from various parts of the stem. +Fig. 10.--Adventitious roots of a plant. + +The adventitious roots are often called "false" roots. + +MORPHOLOGY + +SUMMARY + +Parts of a Plant.---The body of a plant is built up of root and shoot. +The shoot is divided into stem and leaf. The axis of the plant is built up of the root and stem. The root is the descending axis and the stem the ascending axis. + +From a morphological point of view, we speak of the various parts of a plant as roots, stems, leaves, flowers, fruits, seeds, seed-structures, +stem-structures, leaf-structures, and hair-structures. +This is a very general statement, but it is true from a physiological standpoint. The wallflower plant is built up of the same parts as the bean. + +Parts in a Sense.---The following table shows the parts present in the seeds of the Bean and Indian Corn. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
BeanIndian Corn
Coversings of Fruit.Absent.Present.
Seed-Cots.Tufts and tufted.Tufts and tufted.
Exudate.Plumule and two cotyledons.Plumule and one cotyledon.
Marking in seed coat.None.Marking in seed coat, not seen.
This is a Dioicous plant because it possesses two cotyledons.This is a Monocotyledonous plant because it only possesses one cotyledon.
+ +By the permination of the seed we mean the changes that a seed goes through during its early development. The radicle is produced by the elongation of the radicle. A secondary root is a root which is produced from the primary root. Adventitious roots are produced from any part of the plant and without any regular order. + +QUESTIONS ON CHAPTER II. +(1) Define the term member. Name the members which can be found in any plant you may select. +(2) What are roots? What kinds of roots are there? +(388). +(3) Suppose a piece of the axis of some flowering plant was shown to you, what appearances would enable you to decide whether it was part of a stem or part of a leaf? +(4) Describe the structure of a grain of wheat, and the mode of its germination. (1883). +(5) How do you suppose the seeds of the bean and of the wheat. +(687). +(6) From what part of a stem does a branch grow ? Illustrate your answer by a sketch. + +CHAPTER III + +ANATOMY--STUDY OF THE SHOOT + +Shoot.--Stems and leaves are so intimately connected that it is impossible to treat of one without reference to the other. +The term shoot is applied to all parts including both the stem and its leaves. At the apex of the shoot there is, as a general rule, the growing point, from which the leaves and branches are pro- +duced. The leaves are arranged in such a manner that they cause them to overlap the apex, forming a bud. The structure of the tip of the shoot can be made out by the aid of a hand lens. + +*Pericarpium.*--The outer covering of the shoot and it is surrounded by a number of minute leaves. + +Expt. 7.--Take a twig of the Horse Chestnut, and make a longi- +tudinal section so as to pass through the apex. + +Expt. 8.--Take a hand lens. + +A series of leaves, the largest on the outside and the smallest near the centre of the bud, will show how they cause overlapping leaves, the growing point will be fairly easily made out. + +Buds.--A bud is an undeveloped shoot, and from it leaves and branches may be produced. Buds receive different names according to their position on the shoot, but they are all buds from them. If a bud develops into a branch it is known as a *stem-bud*, if foliage leaves are formed from the bud it is called a *leaf-bud*. If flowers develop from the bud it is called a *flower-bud*. + +Buds are often named after their position on the shoot. If the bud is found at the end of the shoot it is called a *terminal bud*, when it grows in the axil of a leaf, an *axillary bud*, if the bud springs from any other part of the shoot it is known as + +CH. III ANATOMY--STUDY OF THE SHOOT 17 + +an adventitious bud, but those are very rare though the ten- +driils of the vine are produced from such buds. + +Some buds may be lateral or dormant, i.e., remain undeplored for some time, and then suddenly become active. Sometimes +buds have been destroyed by frost or accident. Trees in spring may have their leaves destroyed by frost, but after a few weeks a new set of leaves are developed, which are derived from latent buds. Latent buds are more numerous than +save the life of the tree. Even when in the dormant state these buds may give rise to branches, and also give rise to balls such as are often seen, under the bark, in the Beech, Oak, Ash, Lime, etc. Latent buds also give rise to the + + +A small illustration showing a T. Ter- +minal bud; 1, Latent buds. + + + +A stem and leaves, showing buds in +the axils of leaves. + + +knots which are found in timber. If the main shoot of the Oak and Beech be cut down, a dense outgrowth of branches, formed from the base of the shoot, occurs; this is called tillering. The new shoots are usually adventitious buds. It is a very common practice for farmers in the spring to roll the wheat which is sown in winter; this is to make it + +18 +BOTANY FOR BEGINNERS +CHAP. + +tiller. In other cases they have the young growing points eaten off by sheep to produce the same result. +Those buds which persist through the winter are protected with special bud-scales, which are hard and scaly in their nature. The bud-scales of the Oak are dry, those of the Horse-Chestnut sticky, from the secretion which they produce. + +![Fig. 13.—Filtering of Stompy of Elm.] + +In some cases bud-scales may be hairy, and in others perfectly smooth. The bud-scales as a general rule fall off as the bud opens, thus allowing the leaves to expand. + +Expt. 8.—Obtain a small branch of the Hazel, and note the position of the leaf-bud on the upper side of the branch: in the terminal bud, those behind are the lateral ones. + +Expt. 9.—Take a twig from any tree in winter, and keep it in water so that it will remain green. It will show (i) that it will produce leaves from the leaf-buds; if flower-buds are present, these will also develop into flowers; (ii) that it will produce roots from the root-buds; (iii) that it will produce new twigs from the nodes; (iv) that it will produce new shoots from the buds at the base of old branches; (v) that it will produce new buds from the nodes of old branches; (vi) that it will produce new buds from the nodes of old branches when cut off; (vii) that it will produce new buds from the nodes of old branches when cut off and placed in water; (viii) that it will produce new buds from the nodes of old branches when cut off and placed in water and kept in water; (ix) that it will produce new buds from the nodes of old branches when cut off and placed in water and kept in water and allowed to grow for a short time; (x) that it will produce new buds from the nodes of old branches when cut off and placed in water and kept in water and allowed to grow for a short time and then allowed to grow for a longer time; (xi) that it will produce new buds from the nodes of old branches when cut off and placed in water and kept in water and allowed to grow for a short time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed to grow for a longer time and then allowed togrow + +III +ANATOMY-STUDY OF THE SHOOT + +Exr.t. 10.-Cut sections through the apex of the buds of the Horse Chestnut and Sycamore. Note: + +(i) The young leaves. + +(ii) The young leaf-bases. + +(iii) The apical growing point. + +(iv) The arrangement of the different parts should be shown in a sketch. + +Kinds of Plants.-Plants may be annual, biennial, or perennial, i.e., they may last one, two, or more years. Annuals live only one year, grow up, bear flowers and then die. Wheat, Barley, Peas, Beans and Mignonette are examples. + +Biennials Plants are those which during the first year of growth store up reserve materials, these substances being used for the production of flowers and seeds in the second season. Thus, the Carrot, Turnip, Cabbage, Foxglove, and Beet, are typical examples. + +Perennial Plants live and grow for three or more years. They include the Rose, the Oak, the Ash, and Hawthorn; or they may be herbs, like the Daisy, Snowdrop, Wild Hyacinth, and Primrose. The herbaceous perennials have roots which store up food. Leaves and flowers are produced; the aerial parts die down each year. + +The Ascending Axis.--The ascending axis is a very important part of the plant; though leaves may be absent, and in a few cases even the stem itself may be always present. The stem bears buds, leaves, flowers, and fruits, and connects the leaves with the roots. If the stem is produced by a bud on another stem it is called a lateral or terminal. The place on the stem from which a leaf arises is termed a node, and the space between two nodes is termed an inter-nodal space. In some plants such as the Lily of the Stitchwort, and in a few cases adventitious roots may spring from them, as in the Ivy. + +The Descending Axis.--The descending axis may be soft and green, and die down at the end of the season, when it is called a herbaceous stem. Herbs are plants which fulfil their life functions within a short time; they are called herbs. Annuals, such as the Stock, Oats, and Indian Corn, also produce seeds at the end of their period of growth. +c 2 + +30 +BOTANY FOR BEGINNERS +CHAP. + +**Shrubby Stems differ from those named above in being hard and woody. They are larger than herbaceous stems; but smaller than the stems of trees. A shrub is a dwarf tree with a number of permanent woody stems, which divide from the bottom, and each stem bears leaves. The branches may be more slender, and (b) in not growing more than twenty feet high. The following are typical shrubs—Box, Heath, Rose, Rhododendron, Rosemary, and Sweet Briar.** + +A diagram illustrating herbaceous, shrubby, and woody stems. +A: Herbaceous stem. +B: Shrubby stem. +C: Woody stem. +D: Stem of a woody plant. + +**Woody Stems are large, and last for a number of years; they show rings of growth if cut across. Our forest trees such as the Oak, Beech, Fir, Lime, and Ash have woody stems. Aerial Stems grow above the ground, as those of the Oak, Willow, and Foxglove. Several forms of aerial stems are distinguished.** + +The *Ramus* is a stem which creeps along the surface of the ground, as the *Ligustrum* (Fig. 12). It has leaves at its tips and leaves from its upper surface, e.g., the Strawberry (Fig. 15). + +The *Off-set* is a stem which is produced from the parent stem; it creeps on the ground for a short distance and then takes root, e.g., the House-leek (Fig. 16). + +The *Stolon* is a branch which takes root at its end, thus producing a new plant, e.g., Couch-grass (Fig. 17), Gooseberry, and Currant. + +**HERBACEOUS SHRUBBY WOODY STEMS** + +**FIG. 14.—Diagram illustrating herbaceous, shrubby, and woody stems.** + +III ANATOMY--STUDY OF THE SHOOT 21 + +The Sucker is an aerial branch given off by an underground stem; it runs for a short distance beneath the surface, and then strikes upwards, forming a new plant, e.g., the Rose and Mint. + +Subterranean Stems grow beneath the surface of the ground, and are often termed, in popular language, roots. + +Fig. 15.--Runner of Strawberry. + +Fig. 16.--The Offshoot of the House-ink. Fig. 17.--The stolon of the Couch-grass. + +Many perennial plants are able to exist throughout the winter by means of underground stems. + +The rhizome is an underground stem which produces both roots and leaves. The roots are produced from the under-surface of the stem, and the leaves from the upper. Rhizomes + +A diagram showing a runner of strawberry. +A diagram showing the offshoot of house-ink. +A diagram showing the stolon of couch-grass. + +22 +BOTANY FOR BEGINNERS +CHAP. + +differ from roots in producing leaves and buds. Solomon's Seal and the Iris produce rhizomes (Fig. 18). +The Tuber is a swollen underground stem, and in it there is stored up large quantities of reserve materials for the production + +A diagram showing the structure of a tuber, with labels indicating different parts: a b c d e f. + +Fig. 18.--Diagram of Solomon's Seal, a bud of next year's aerial growth; b--scar of this year's growth; c, d, e, scars of previous year's aerial growth; and f--root. + +Fig. 19.--Part of Potato plant, with the old dark tuber in the centre. +of a new plant. The Potato tubers are produced from the ends of stolons, and thus are formed a little distance from the parent + +**III ANATOMY-STUDY OF THE SHOOT** + +plant. The so-called **eye** that are found on the outside of a potato are in reality buds, from which the next year's growth will take place. The parent plant dies after the production of the tubers, but not before large quantities of reserve materials have been accumulated in the tubers for the next year. If the alternate leaves of the Potato plant be covered up with soil, their growth will be checked and they will produce underground tubers instead of leaves and the Earth-nut also produces tubers. + +The **Bud** is a modified stem often seen with young plants of many plants. It consists of a short thickened stem with a large number of crowded, over- lapping leaves. In this bud is stored a large quantity of reserve material for the growth of the next season's plant. The bud may have several sheathe one another, but in the Tiger Lily they only overlap. The bulb is closed by a thick covering. The Onion, Wild Hyacinth, and Daffodil are examples of plants that produce bulbs. + +The **Corm** is a very solid fishy stem, usually below ground, from which the bulb, solid, rounded, main axis, full of reserve materials grows freely. + +Ex. 21.--Obtain from a greenhouse a piece of the runner of a Strawberry plant. Note-- + +(1) How the runner gives off roots. +(2) How the leaves develop from the upper surface of the nodes; the roots spring from the lower surface of the stem. + + +A longitudinal section showing the structure of a corm (Crocus). The shoot (stem) is shown at top left, with two leaves (one at top right and one at bottom right), and three buds (one at top center and two at bottom center). + + +Fig. 21.--Corm of Crocus. + +23 + +34 +BOTANY FOR BEGINNERS +CHAP. +EXPT. 12.—Take a few plants of the Couch-grass—which can be found in most meadows and in cornfields, and examine them. Select one which has been growing for some time. + +That branch is given off above the level of the ground, and then bends downwards and forms a root at its end. + +EXPT. 13.—Take a plant of a cherry-plant with its attach- +ment to the underground stem it obtained, the way in which it is pre- +cured can be seen by examining it. The underground stem +produces a root, which runs for a short distance beneath the +ground, and then breaks through the soil and comes to the surface. + +EXPT. 14.—Dig up a thyme, either of Solomon's Seal or a Buckwheat. +The thyme will be found to have a root which grows down with which to remove the surface soil. Follow the stem so as to uncover it without breaking it. The old leaves produced by the leaves of previous years. These are gathered together in a bunch, and are called a leaf-stem. The new leaves, which will break through the ground next season. + +(6) The growing point, which is protected by scale leaves. + +EXPT. 15.—Take a Potato tuber and examine it. The eyes, which are buds, will be seen as small dark spots. If a young tuber is examined, the eyes will be seen on the outside of the tuber, but under the skin of the tuber in two and notice how thick and flexibly it is. + +EXPT. 16.—Obtain a bulb of the Daffodil and a Canna corm. Examine and compare them. + +(1) The bulb which is made up of scale leaves, many of which are dead and fall away each year. + +(2) In the corm the stem is far larger than in the bulb, but the leaves are not numerous. + +**Parasitic Stems.—In a few cases stems are so modified that they can no longer support another plant, and extract from it these materials which are necessary for their existence. Plants of this description are called parasites.** The Dodder is generally considered to be a parasite upon the Dodder-Clover, the Nettle, and the Willow. When the seeds of the Dodder germinate a long filament is formed, the free end of which moves round and round in search of a host-plant—as +the plant does not grow very fast—until it finds one. The host-plant is found it twines closely about it like a climbing plant. Suckers are produced from those parts of the filament which are in close contact with the host, and these pierce the host, and work their way inwards to obtain food. + +III ANATOMY-STUDY OF THE SHOOT + +Expt. 17.-If a specimen of a plant can be obtained, which has been attacked by the Dodder, it should be examined. Note— + +(i) The dodder is attached to the host. + +(ii) How the suckers are produced. + +Climbing Plants.—Plants climb over the shoulders of their weaker brethren for two reasons; (a) because their shoots are far too weak to support themselves, and (b) to expose their leaves to light. Climbing plants have various means of adhesion, viz.: (1) Those which climb by the aid of roots, such as the Ivy, the use of hooks, as the Bramble and the Yellow Bedstraw; (2) those which climb by means of stems, as the Convolvulus and the Hop. (4) By suckers, as in the case of the Ivy, which come in contact with any convenient support and cling to it, as the Clematis and the Vines. + +Rootlet-Climbers.—The rootlets are adventitious roots which are produced from the stem. When these come in contact with a wall or the bark of a tree they give off a mucilaginous substance by which they adhere to the support. The rootlets are produced on the shady side of the stem, but they may not all be fixed to the support, but may be divided up, forming shaggy branches (Fig. 22). + +Hook-Climbers.—The Bramble is able to support itself by weaving its way through the trees which grow in its neighbourhood. It is able to do this because it produces hooks, by the aid + +A drawing showing a plant with a hook-like structure. +R = Abutilon roriflorum + +26 +BOTANY FOR BEGINNERS +CHAP. + +of which it fixes itself to walls, trees and shrubs. Cleavers, +which is a struggling, rough and matted plant found in hedges, is another good example of a plant which climbs by means of +hooks or tendrils. + +**Stem-Climbers.**—When the stem of the hop plant comes out of the ground its first two or three internodes grow up erect, and at their nodes which are produced from the top of the first-formed leaf, the stems commence to bend slowly and gracefully to one side and travel steadily round the point of the compass, describing a complete circle in the direction of the hand of a watch moving over its face. Should the twining stem come into contact with a support, the part which it strikes is seized by the hooks which are well developed on its surface. The stem still grows at the apex and goes on twining, thus climbing more and more about the support. The Bindweed or Convolvulus also climbs by means of its tendrils. It will climb in the opposite direction to the Hop, i.e., towards the east; this is called twining to the left. The Blind-vein turn round towards the east; this is +called twining to the right. + +**Plants which Climb with Sensitive Organs.**—This + +Fig. 13.—The hooks of the Bramble. + +**Fig. 14.—Diagram illustrating plant climbing by means of tendrils.** The Hooked-leaf (Solanum) climbs by means of its tendrils, which are shown here in a right-handed figure how the Convolvulus twines to the left. + +from the west through the north +turned twining to the left (Fig. 24). + +III +ANATOMY-STUDY OF THE SHOOT +27 + +division can be subdivided into two classes, viz., leaf-climbers and tendril-climbers. +A good example of a leaf climber is the familiar Clematis. The upper, younger internode of the Clematis goes wandering round and round in slow circles after the manner of the twining + +A diagram showing the climbing stem of a plant. +Fig. 15.—Climbing stem of Honey- +ivy (Vincetoxicum hirundinaria). + +A diagram showing the climbing stem of a plant. +Fig. 16.—Climbing stem of Con- +volvulus arvensis (field bindweed). + +plants. This brings the leaves in contact with the stems, twigs, or the trellis-work erected by the hand of man. Such objects as these are seized slowly but surely by the leaf-stalks of those leaves which come in contact with them. The leaf stalks are sensitive and turn round the object touched. + +A tendril is another structure which is sensitive to touch and + +28 +BOTANY FOR BEGINNERS +CHAP. + +is used for climbing. These organs, with their ready response to any contact and their power of turning round and clinging to objects, are the most highly developed in the class of climbing plants. The tendrils are formed from various parts of plants; thus, in the Passion flower (Passiflora), the leaf-stalks are modified into tendrils of the Vine is a flower-stalk; that of the Sweet Pea, the whole blade of a leaf; that of the Cucumber and its allies arise from the stem. In some cases, however, the organ is a body found at the base of the leaf-stalk and known as stipules. The tendrils are usually long and flexible, and can move round and round in search of a support. + +In some orchids, when their movements are arrested by a support, form adhesive masses at their free ends, as in the Virginian creeper, which adhere to the walls and sides of houses. Soon after the tendrils of the Virginian creeper have made contact with a wall they were, upon a wall, their tips swell, become red and form little swollen knobs. When these knobs make contact with the wall, small projections are produced which imbed themselves in the surface of the wall. This crevice and seem to give out a cement which binds them to the support (Fig. 27). + +Expt. 19.--Examine a piece of Ivy from an old wall; examine it. Note the following points: + +(i) That portion of the stem which grows up from the roots. + +(ii) That the roots grow on a portion of the stem which is turned over. + +(iii) That the root dries up, and forms a beard on the stem. + +Expt. 19.--Examine branches of the Rose or Bramble. Notice-- + +(i) For how many times or two off and on how much of the branch comes away with this plant. + +(ii) Frickles may be used for protection as well as for climbing. + +A diagram showing a plant with tendrils growing from its stems. + +Fig. 27.--Virginian Creeper. +(From Jour. Bot., 1854, p. 306.) + +**ANATOMY—STUDY OF THE SHOOT** + +31 + +Expt. 25.—Obtain a portion of the Hop-plant or Honeysuckle with its support. Note— + +(i) How long and in what direction the stem has moved. Compare with Fig. 30. +(ii) Note the difference in the direction of twining. + +Expt. 26.—Obtain a portion of the Cucumber plant, or a piece of Clematis showing the sensitive leaf-stalks. Examine how the stalks clasp the support. + +Fig. 31.—Obtain a tendril-bearing plant, such as the Vine, Vetch, Sweet Pea, Cucumber, or Bryony. Examine to see what parts of the plant are modified into a tendril. Compare with a portion of the Virginian Creeper. + +The **Shape of the Stem**.—Stems may be round or cylinder-shaped, like the *Peach* ; irregular, as in the *Flax* stem ; or flat, like the *Daffodil* ; square, like the *Deadnail* ; or ribbed, like the *Wall-flower* (Figs. 28–32). + +Fig. 28. +Fig. 28. +Round stem, +with section. + +Fig. 29. +Fig. 29. +Round stem, +with section. + +Fig. 30. +Fig. 30. +Round stem, +with section. + +Fig. 31. +Fig. 31. +Thickened stem, +with section. + +Fig. 32. +Fig. 32. +Curved +ribbed stem, +with section. + +Some stems are solid at the nodes, but hollow at the internodes, e.g., Fool's Parsley. Others are solid throughout as in the Wall-flower. + +**Surface of the Stem**.—Stems differ not only in their shapes but also as regards the nature of their surfaces. Many stems are completely covered with hairs, prickles, or thorns. If the surface is smooth, it is termed *glabrous* ; if hairs are present, + +39 + +30 +BOTANY FOR BEGINNERS +CHAP. + +The Wallflower is covered with spindle-shaped hairs, and upon the Stock branched hairs are found. +In the Stinging Nettle large hairs for protection are found. When the tip of such a hair enters the finger it breaks off and a fine stinging sensation is felt. This is a most interesting sensation. +The surface of a stem may be covered with prickly structures, which are produced by the modification of hairs, or other structures. The hooks on the stems of the Hop, Cleavers, and Borage are true thorns, but they cause no injury, because they are de- +veloped from the surface of the plant. The struc- +tures found on the stems of the Hawthorn, etc., which are formed from branches which have undergone change so as to protect the plant from injury, are called thorns. +The prickles of the Hawthorn are modified leaves ; they are, as a rule, solid and pointed. The prickles of the Bramble and Rose are formed not only by the development of the surface covering of the plant, but also by a deeper layer which causes their formation. The name *emergens* may be given to them. + +Expt. 23.—Cut across the stems of the following as to show that they are either solid or hollow : -Dandelion, Daffodil, +Lily, Dendrlet, and Mignonette. Compare their shapes and notice if the stems are solid or hollow. + +Expt. 24.—Examine as many stems as possible to see if they are + +Fig. 23.—Spines on the Hawthorn. +Fio. 23.—Spines on the Hawthorn. + +30 + +**III ANATOMY--STUDY OF THE SHOOT** + +smooth or hairy. Similary describe the surface of every stem met with. If this is done for a few weeks, the reader will have a very valuable series. + +Ex. 26.--Cut off a few branches of the following plants: Hawthorn, Rose, Snow Bramble, Hop, Cherries, Borings, and prickly Comfrey. Examine and make a sketch of each. Note the leaves on them. Sections should be made through the stem so as to show the connection of the covering with the stem. + +**Leaves.--** Leaves are developed as lateral outgrowths from the growing point of the stem. They are often said to be flattened out stems. They may be deciduous, that is, they may fall off at the end of the season, or they may remain on the tree for a number of years. The Oak produces the former kind of leaves and the Holly the latter. + +The Oak has two kinds of leaves. One is found in the order, the older ones being found on the base of the young twig and the younger ones near the apex. There are four kinds of leaves which grow on the branch. + +**Foliate-leaves,** or the ordinary green leaves of the plant. + +**Scale-leaves,** or those found covering the bud. + +**Floral-leaves** are found close to the flower, which they as a general rule cover. + +**Floral-leaves:** some of these are coloured, and the flower is born up by them. + +All kinds of leaves are not found on every plant. Most plants possess foliage leaves, but the Dodder has only scale leaves. In the Lily of the Valley, the foliage leaves, bracts, and petals are leaf-like structures developed. In the Wallflower only the first and last are found. + +**Expt. 26.--Collect branches of the Oak and Fir in winter. Notice that the twigs of the Oak are without leaves, but the Fir is well covered with them.** + +SUMMARY. + +**Shoot.--** Full up of stem and leaf. The growing point is at the apex, as is mentioned by Mr. Huxley. + +A **bud** is an undeveloped shoot. There are three kinds of buds, viz., apical buds, lateral buds, and terminal buds. This bud at the apex of a stem is called the terminal bud, and those behind it are called lateral buds, and if it is later + +31 + +32 +BOTANY FOR BEGINNERS +CHAP. + +are produced in the axils of the leaves they are axillary buds. An adventitious bud is one which is produced out of the regular order. A buntine or a bud that grows out of a leaf stalk is an adventitious bud. +Tillering is a term which is used to describe what takes place when a plant produces a large number of branches from the base of the stem. +Plants may be either annual or perennial. Annuals live only for a single season. (2) Perennials plants those during their first year of growth produce flowers and seeds, and then die. The second season produce flowers and seeds. They only live two years. (3) Biennials live for two years. The first year produce flowers and seeds, and the second year produce leaves and roots. The leaves are called phylloides. +The ascending axis produces leaves, and connects the leaves with the root system. The leaves are attached to the stem by a petiole or termed node, and the space between two nodes is called an internode. +Stem.--There are three kinds of stems: +Herbaceous.--Plants that grow up, and die down each year. +Shrubby.--Plants that grow steadily, not above twenty feet high, and grow above ground. +Aerial Roots grow above the ground. They can be divided into: +The Runner, which creeps along the ground, like the Strawberries. The +Other Roots are called Tuberous Roots, because they are tuberous. +The Stolon is a branch which takes root at its end. The Stolon is +called a runner when it grows horizontally on the ground, like the Oak. +Subterranean Stems grow beneath the ground and can be divided +into: (1) Those which creep along beneath the ground and pro- +duce both roots and leaves. The Tuber is a swollen underground stem, +which is used for food storage. It is found in many plants such as +ground hul, and is modified for storing up food for future use. +(2) Convolvulus has a tuberous stem which is used for storing water. +Parasitic Stems are produced by parasites. A parasite is a plant in which the roots are modified to obtain nourishment from another plant. +Clover Climber is a good example of such a plant. +Climbing Plants are those plants which climb other plants. These are +called: Rooting Climbers, like the Ivy. Hood Climbers, like the +Bramble. Stem Climbers, like the Honeysuckle and Convolvulus; +and Leaf Climbers, like the Ivy and Wisteria. They attach themselves into (a) leaf +and (b) tendril climbers. +Mosses have no true stem, but a round, square, ribbed, and trangular. They may be smooth or hairy. The surface may be covered with _spines_ or _cortices._ +Leaves are produced as outgrowths of the growing point of the stocm. +There are two kinds of leaves: (1) Stem Leaves; (2) Flowering Leaves. +Leaves are the ordinary green leaves of the plant. Scale Leaves are +found on some plants in young buds. Bractlets Leaves are found at +the base of the flowers. Floral Leaves are modified leaves which go to +build up the flower. + +III +ANATOMY-STUDY OF THE SHOOT + +33 + +QUESTIONS ON CHAPTER III. + +(1) Of what use to the plant is the stem? How can you distinguish a stem from a root? + +(2) What are the essential differences between a node and an internode? Illustrate your answer by examples. (1884.) + +(3) What is meant by annual, biennial, and perennial plants? Explain the mode of annual growth in length of the rhizome of Solomon's Seal. (1886.) + +(4) State what is meant by annual, biennial and perennial plants, giving examples. (1886.) + +(5) What is meant by shoot— + +(a) The runner. +(b) The rhizome, +(c) The tuber. +(d) The offset, +(e) The bulb? +(f) What is a corm? + +(6) What kinds of stems are there? Give examples. + +(7) Where is the growing point of a shoot found, and how is it connected with the rest of the shoot? + +(8) If all the leaves on a Currant bush be plucked in spring, what will happen to the plant? + +(9) How are the knots found in timber produced? + +(10) Define the term "flattening." When and how does tillering take place? + +(11) What is a parasite? Give an account of the mode of life of the Dodder. + +(12) Give examples of plants which climb by means of tendrils, and explain their mode of attachment. (1887.) + +(13) Give a classification of climbing plants. How do they climb? Are there any that do not climb? + +(14) What is the structural difference between a prickle (as in the Rose) and a spine (as in the Blackthorn)? (1884.) + +D + +CHAPTER IV + +THE STUDY OF THE SHOOT (Continued) + +Parts present in a Perfect Foliage Leaf.—In a perfect leaf the following parts are present. + +The blade or leaf-sheath, the portion of the leaf. + +The petiole or the stalk of the leaf. + +The Sheath which forms the base of the leaf. It is wider than the petiole, and may sheathe the stem. + +In most leaves, when other parts of the leaf are absent, the leaf is said to be sessile, as in the Wall-flower. If the sheath is not developed, but the blade is prolonged into a stalk, this is called petiolate, as in the Cherry. If all the parts are present, as in the Filewort and Acanthus, they are said to be pinnately compound produced from the base of the leaf, as in the Rose and the Pea; these are termed Sipules. If stipules are present the leaf is said to be stipulate, and if they are absent exstipulate. + +The Venation of Leaves.—The veins of a perfect leaf are usually parallel, but in some cases more or less divergent. The softer parts are supported; they also bring the sap from the stem and distribute it to the leaves. The veins may be simple or reticulate—veined. The former arrangement is found in monocotyledonous plants and the latter in dicotyledons. In a parallel-veined leaf, the veins run parallel to one another from the base of the blade to + +Fig. 34.—Perfect leaf of a Monocotyledonous plant. The blade is petiolo- +dose, &c. without stipules. + +CH. IV +THE STUDY OF THE SHOOT + +The apex, and they are connected by smaller cross veins, as in the leaf of the Lily of the Valley. The reticulate-veined leaf differs from the parallel-veined leaf in possessing one or more midribs, from which veins are produced, resembling a network, another to give the leaf the appearance of a reticulate-veined leaf, such as a reticulate-veined leaf (fig. 60). If the leaf only possesses one mid-rib, the leaf is said to be uni- cotiate; if it is divided into a number of divisions, and each lobe possesses a mid-rib, it is said to be multicoiate. As in the Oak, Beech, Poppy, and Dan- delion, are unicotiate, while the Sunflower, Rose, and Butter- oil plant, and Fig, are multicoiate. +The veins of a leaf give it strength ; it depends upon the mode of life of the plant what kind of leaves will be produced. Plants which grow in a very exposed position generally have narrower leaves than those which grow in sheltered places. + +Fig. 35.—Veneration of a leaf. + +Fig. 37.—Multicoiate and palmate leaf of the Horse-chestnut. + +D 2 + +36 +BOTANY FOR BEGINNERS +CHAP. + +leaves have the veins finely divided so as to give mechanical support, as well as to expose as great a surface to the water as possible. In the case of marsh plants like the water Crowfoot, which has two kinds of leaves, it is only the submerged ones which are divided. + +Exer. 38.-Collect a number of leaves and arrange them into--- +(i) Two series according to their venation. +(ii) The two divisions according with the arrangement of these. + +Arrangement of Leaves on the Stem.--Leaves grow from the nodes of the stem, and the arrangement of these + +Illustration showing alternate leaves. +Fig. 38.--Alternate leaves of Ficaria verna + +Illustration showing opposite leaves. +Fig. 39.--Opposite leaves of Caltha palustris + +depends upon the length of the internodes and the size of the leaves. The leaves on a given plant are always inserted at points which bear a certain relation to one another, which may be expressed in a numerical manner. The arrangement of leaves on the stem is called phyllostaxis. In a phyllostactic leaf only is produced at a given node, and from the node higher up the stem but on the opposite side another springs the phyllostaxis is said to be alternate, as in the Wallflower. + +IV THE STUDY OF THE SHOOT 37 + +When two leaves spring from the node and face each other, the arrangement is called opposite; if the leaves higher up are placed at right angles to the first pair, the arrangement is called decussate—the Decussate is a good example of this. If more than two leaves are produced at a node, they are termed whorled leaves. +The Bed-straw and Cleavers are examples of this arrange- +ment. + +The most common ar- +rangements of leaves are +the alternate, opposite, +and whorled. The so- +called alternate arrange- +ment can be further investigated by drawing a spiral round the stem from one leaf until the leaf vertically above is reached. In the case of the Wallflower or Oak the spiral goes round the stem clockwise, but in the case of the Willow or Poplar, the leaves, not counting the leaf at which the spiral commenced, are touched by the apical. This is known as a $\frac{3}{4}$ arrangement. The same phytotaxon is found in the Pear, Poplar, and Walnut. In the Pinnae-the leaves form a $\frac{3}{4}$ phytotaxon. + +Fig. 45.—Whorled leaves of Cleavers. +Fig. 46.—Diagram Illustrating phytotaxon of Oak. + +Start of Spiral +Twig of Oak. + +38 +BOTANY FOR BEGINNERS +CHAP. + +**Expt. 8.**—Collect and examine branches of the Oak, Willow, Poplar, Belf straw, and Elm. Determine their phytostasis, and mark on the stem the number of cycles made in passing from one leaf to another. This can be done with a piece of chalk. The leaves are also numbered so that the arrangement will be seen at a glance. + +**Different Kinds of Foliage Leaves.**—When the leaves are attached to the underground stem, as in the Daisy and Dandelion, they are called radiculose. If they grow on an aerial stem, as the leaves of the willow, they are apophyllous or caulescent leaves. + +**Foliation.**—Leaves may be either simple or compound. Leaves are called of a single piece, as in the simple when the blade consists of one leaf only, as in the Nettle. The blade may be divided, but unless it is cut down to the midrib it is still a simple leaf. Compound leaves are cut into a number of distinct parts, as in the Pea and the Ash. Each separate part of such a leaf is called a leaflet. + +**Simple Leaves.**—Leaves vary much in shape or general outline. + +Fig. 42.—Diagram illustrating leaf phytostasis. +Fig. 43.—Diagram illustrating leaf phytostasis. + +Fig. 44.—Radical leaves of the Primrose. + +IV +THE STUDY OF THE SHOOT +39 + +Simple leaves receive the following names, according to the shape of the blade:- + +*Lanceolate*, when the leaf is from two to four times as long as it is broad and taper at both ends, e.g., Wallflower (Fig. 43). + +*Linear*, when the leaf is nearer the base than the apex, e.g., Guilder-Rose (Fig. 45). + +*Cordate*, when the base is shaped like a heart, e.g. Lime-Tree. + +*Sagittate*, when the base possesses pointed ends extending like an arrow backwards, e.g. Convolvulus (Fig. 48). + +*Ovate*, when the base is rounded and is nearer the apex than the base, e.g. as in some of the Rock-Roses, and leaflet of Wood-Sorrel (Fig. 49). + +Fig. 43.—Lanceolate leaf of Wallflower. +Fig. 46.—Ovate leaf of Lilac. +Fig. 47.—Cordate leaf of Deadnettle. + +*Oblanceolate*, when the lanceolate leaf has a wider part which is nearer than the base, e.g. Dog Violet and *Daisy*. + +*Spatulate*, when the leaf is like a spoon, with a rounded portion near the apices, e.g. Daisy. + +*Reniform*, when the leaf is kidney-shaped, e.g. Ground Ivy (Fig. 50). + +*Linear*, when the leaf is very long and narrow, e.g. most Grapes (Fig. 51). + +*Oval*, when the leaf is oval, e.g. Apple (Fig. 54). + +*Atrorubinate*, when shaped like a needle, e.g. Fir. + +Fig. 43.—Lanceolate leaf of Wallflower. +Fig. 46.—Ovate leaf of Lilac. +Fig. 47.—Cordate leaf of Deadnettle. + +40 +BOTANY FOR BEGINNERS +CHAP. + +Many of the above terms are used to describe the shapes of the leaflets of compound leaves. + +Fig. 45.—Simple leaf of Arum. +Fig. 43.—Ovate leaf of the Wood-Sorrel. +Fig. 40.—Drooping leaf of the Daisies. +Fig. 42.—Spathulate leaf of the Darby. + +**Compound Leaves.** If the blade of the leaf is divided down to the mid-rib it is said to be compound. The separate parts of the blades are called leaflets ; these are given off from + +Fig. 79.—Reniform leaf of Ground Ivy. +Fig. 53.—Diagram of Linear leaf. +Fig. 78.—Elliptical leaf of Apple. + +the mid-rib. The leaflets separate from the mid-rib or petiole in the same way that the entire leaf separates from the stem, i.e., without tearing. They may be pinnately or palmately divided. The following are examples of the latter kind. + + + + + + + +
Fig. 79.—Reniform leaf of Ground Ivy.Fig. 53.—Diagram of Linear leaf.Fig. 78.—Elliptical leaf of Apple.
+ +THE STUDY OF THE SHOOT + +41 + +Ternate or cleft-leaf, the leaf is built up of three leaflets, as in the Clover and Wood-Sorrel (Fig. 53). + +Bifid, when the leaf is ternate, but each division is divided again ; in fact, three leaflets divided into three leaflets, as is the case with the Honeysuckle. + +Palmate, when the leaflets radiate from the leaf-stalk like fingers from the palm of a hand. Hence Chestnut (Fig. 37). + +When the leaflets are arranged along each side of the midrib, they are said to be like a feather or pinnate. + +Fig. 53.--Ternate leaf of Wood-Sorrel. +Fig. 54.--Bifid leaf of Strawberry. +Fig. 55.--Palmate leaf of Bumbleberry. + +There are two kinds of pinnately divided leaves--those with an equal number of leaflets along each side of the mid-rib, and those with an odd leaflet. The former are called *paripinnate*, and the latter *superimposed*. + +In *Lonicera* and *Clematis* there are an equal number of leaflets on each side of the mid-rib, as in the Bitter Vetch. + +42 +BOTANY FOR BEGINNERS +CHAP. + +Imperspicuous, when there is an odd leaflet, as in the Rose and Robinia (Fig. 58). +Rhipidiate, when the leaflet is again divided, as in the common Meadow Rue (Fig. 39). +Trifidate, when the divisions are carried a little farther and each part is in three, as in the Lesser Meadow Rue. +The Margin of Leaves.—The margin of leaves vary in different ways. The following terms are used to describe them :- +Entire, if the margin is undivided, as in the Wallflower (Fig. 60). +Fig. 55.—Imperspicuous leaf of Robinia. +Fig. 59.—Rhipidiate leaf of Acacia. + +Scrobiculate, if the margin is divided up into tooth-like divisions, like a saw, and they point towards the apex, the above term is used, e.g., Deadnettle. +Dissected, if the teeth are again divided, as in the Elm. +Crenate, if the teeth are rounded, as in the Ground Ivy. +Dentate, if the teeth point outwards, as in the Gledder Rose. + +43 + +THE STUDY OF THE SHOOT + +43 + +Ciliated, if the margin is fringed with fine hairs like the Beech. + +Spiny, if the teeth are long and very sharp, as in the Holly. + +Apex of the Leaf.—The apex of the leaf may be sharply pointed, as in the Oak, Ash, and Elm; obtuse; and if the end is long and pointed, acuminate (Fig. 6). + +Further Kinds of Simple Leaves.—When the leaf is + + +A diagram showing different types of leaf margins. +1. A ciliate leaf margin with fine hairs. +2. A spiny leaf margin with long, sharp teeth. +3. An apex that is long and pointed, acuminate. +4. An apex that is long and pointed, acuminate. +5. A serrate leaf margin with teeth. +6. A serrate leaf margin with teeth. +7. A serrate leaf margin with teeth. +8. A lobed leaf margin with multiple lobes. +9. A lobed leaf margin with multiple lobes. +10. A lobed leaf margin with multiple lobes. +11. A lobed leaf margin with multiple lobes. +12. A lobed leaf margin with multiple lobes. +13. A lobed leaf margin with multiple lobes. +14. A lobed leaf margin with multiple lobes. +15. A lobed leaf margin with multiple lobes. +16. A lobed leaf margin with multiple lobes. +17. A lobed leaf margin with multiple lobes. +18. A lobed leaf margin with multiple lobes. +19. A lobed leaf margin with multiple lobes. +20. A lobed leaf margin with multiple lobes. +21. A lobed leaf margin with multiple lobes. +22. A lobed leaf margin with multiple lobes. +23. A lobed leaf margin with multiple lobes. +24. A lobed leaf margin with multiple lobes. +25. A lobed leaf margin with multiple lobes. +26. A lobed leaf margin with multiple lobes. +27. A lobed leaf margin with multiple lobes. +28. A lobed leaf margin with multiple lobes. +29. A lobed leaf margin with multiple lobes. +30. A lobed leaf margin with multiple lobes. +31. A lobed leaf margin with multiple lobes. +32. A lobed leaf margin with multiple lobes. +33. A lobed leaf margin with multiple lobes. +34. A lobed leaf margin with multiple lobes. +35. A lobed leaf margin with multiple lobes. +36. A lobed leaf margin with multiple lobes. +37. A lobed leaf margin with multiple lobes. +38. A lobed leaf margin with multiple lobes. +39. A lobed leaf margin with multiple lobes. +40. A lobed leaf margin with multiplelobes + + +Fig. 6a.—Diagram of margins of leaves. 1, ciliate ; 2, serrate ; 3, ovate ; +4, obtuse ; 5, entire ; 6, dentate ; 7, cuneate. + +split up into a number of divisions, and these do not cut down to the mid-rib, the following terms are used :- +Palmateleaf, if the ends extend nearly to the base, e.g., +Moss-leaves. + +Palmatifid, if the cuts extend about halfway from the margin to the base of the leaf, as in the Castor Oil plant. + +Polydental or in the palmatifid leaf the number of divisions is five, as in this shape. + +IV + +44 +BOTANY FOR BEGINNERS +CHAP. + +Pinnatiduct, if the divisions extend nearly to the mid-rib, as in the Poppy. +Pinnatifid, if the cuts extend about half way from the margin + +A leaf with serrated edges. +B leaf with smooth edges. +C leaf with entire edges. +D leaf with lobed edges. +E leaf with entire edges. +F leaf with serrated edges. + +Fig. 61.--Diagram of apex of leaves. A, acuminate ; B, obtuse ; C, acute ; +D, monoserrate ; E, retuse ; F, emarginate. + +to the midrib, as in the Welsh Poppy, and in some of the leaves of the Mignonette. + +Lobed Leaves. These, according to the number of lobes, may be regular or irregular. Five-lobed, etc. + +EXTRACT 39.--Make a collection of leaves. Note and compare their shapes with the figures in the book. +The leaves may be weighed by hanging them with heavy weights between the leaves of a blotting book or even between sheets of paper. If the sheets of paper be changed every day until the leaves are perfectly + +The following table will show how many leaves are found on each plant: + +| Plant | Number of Leaves | +|-------------|------------------| +| Poppy | 5 | +| Mignonette | 5 | +| Welsh Poppy | 5 | + +Note that the leaves of the Poppy and Mignonette are lobed, while those of the Welsh Poppy are not. + +THE STUDY OF THE SHOOT + +dry, the leaves can be mounted on sheets of card board, or on special papers such as the following: + +A diagram showing two arrows pointing to different parts of a leaf. + +6 in. + +4 in. + +Shape. +Margin. +Vegetation. +Name of plant. + +Excer. 31.--Trace out in paper the different forms of any leaves which may be obtained. This can be done by laying the leaf on a sheet of white paper and tracing on the paper with a fine pointed pencil the outline of the leaf, and then cutting out the traced outline with a pair of scissors. The name of the leaf and its shape can be marked on the model, and thus a very good study will be made of the leaf, with accuracy, and will also apprehend the greater truth that there are many more leaves than one can see. + +Stipules.--These, as we have already seen, are outgrowths at the base of the leaf. The texture and colour of stipules vary; thus, if their function is to protect the young leaves in the bud, they may be brown or yellow in colour; if they are used for assimilation, they may be green. In some cases, when the plant, they are green in colour, and large and leaf-like in form. + +There may be two stipules, one on each side of the leaf, as in the case of the oak; or there may be only one, as in the case of the birch; or there may be none at all. Sometimes they are large and are often mistaken for leaves; in fact, they appear to form whorls with the leaves. The stipules are membranous in the rose leaf, where they are represented by a series of teeth along each side of the base, and are called *adnate* stipules. Where + +45 + +46 +BOTANY FOR BEGINNERS +CHAP. + +the stipules unite in the leaf-axil they are called *axillary*, as in +the Pea (Fig. 63). + +**Scale Leaves.**—Scale leaves possess a far simpler structure than foliage leaves. They have no leaf-stalk, and are directly attached to the stem. The young leaves are often covered with scales, which cover the young buds, and they are the only leaves found on under- +ground stems. A few parasitic plants, such as the Broom Rape + +Fig. 63.—Leaf of Pea, F., flower- +stalk ; Sf., stipule ; T., tendrils. + +Fig. 63.—Leaf of Rose, F., leaflets ; +F., petiole ; Sf., stipule. + +which grows on the roots of plants, do not possess any other kinds of leaves. + +**Bracteate Leaves.**—Bracteate leaves resemble scale leaves both in structure and function. They grow at the base of the +stem upon which the flowers are produced. When present the plant is said to be *bracteate*. The bracts may be leafy, leafy, membranous, woody, or coloured. +When the bracts are arranged in a circle, as in the Dandelion, +they form a *bracteole*. If the bracts form a solid cup, as in the + +THE STUDY OF THE SHOOT + +47 + +*scorn*, they form a *capulet*. When a single branch is large and produces a series of flowers it is called a *spadice*, e.g., the Arum. + +**Expt. 33.—Examine the bud of a Paeon and find the stipules. Note—The stipules are large and leaflike. Observe how the end of the midrib of the individual leaf is converted into a tendril. Compare with the stipule of a Rose bud.* + +**Expt. 33.—Note the size, shape, and characters of as many scale leaves as possible during spring, when the buds are opening.** + + +A transverse section of bud of *Paeonia* (C. S.) + + +**Fig. 6a.—Transverse section through bud of *Paeonia*. B, bud.** + +A transverse section through leaf of *Paeonia*. B, bud. + + +**Floral Leaves.—Floral leaves are modified leaves which go to build up the flowers of a flowering plant.** +*Vernation* is the folding of young leaves as shown in figs. 6b, 6c, 6d. The young leaves are folded in the bud is called *vernation or prefloration*. This differs in different plants, and will be considered under two heads, viz., (a) the folding of the individual leaf in the bud ; and (b) the folding of the several leaves in the bud. + + +A transverse section through bud of *Paeonia*. B, bud. + + +BOTANY FOR BEGINNERS +CHAP. + +The arrangement of the individual leaf in the bud is shown below in a tabular form: +48 + +1.—If the leaf is not folded at all, the vernation is plane. +2.—If the leaf is folded along the mid-rib, it is conduplicate, e.g., Boccon. +3.—If the leaf is folded into a number of longitudinal or oblique plats, it is plicate, e.g., Beech. +4.—If the leaf is folded in all directions, it is crumpled, e.g., Poppy. +5.—If the leaf is folded inwards towards the mid-rib, it is involute, e.g., Violet. + +Fig. 60.—Transverse section of bud of Ash. (A. x 3.) +Fig. 61.—Transverse section through bud of Birch. (A. x 3.) + +6.—If the leaf is folded backwards towards the mid-rib, it is revolute, e.g., Dock. +7.—If the leaf is folded up from one side to the other, it is convolute, e.g., Banana. + +The arrangement of the several leaves in the bud is shown below: + +1.—If the leaves in a bud just touch by their margins, the vernation is subulate. +2.—If the leaves in a bud overlap each other, it is imbricate. +3.—If the leaves in a bud overlap each other in regular order, it is revolute or contorted. +4.—If the outer conduplicate leaves in a bud enclose those within in regular order, it is spatulate. + +THE STUDY OF THE SHOOT + +5.—If half of one conduplicate leaf enfolds another, it is semi-crenate. +6.—If one convolute leaf is rolled around another, it is involute. + +Expt. 34.—Cut a transverse section of any leaf-buds met with. + +(i) The arrangement of the individual leaves in the bud. +(ii) The arrangement of the several laminae in the bud. +(iii) The arrangement of the parts in the bud. See fig. 10. + +SUMMARY + +A Perfect Leaf consists of a sheath, petiole, and blade. If the blade is only the uppermost part of the leaf, the sheath and petiole are developed. If the blade is outgrowths at the base of the leaf. Leaves can be exstipulate and stipulate. + +Variation of leaves—two kinds—parallel and reticulate. + +The common arrangements are alternate, opposite, and whorled. In some cases the blade is so long that the former form is not divided down to the midrib, but in latter kind the blade is cut up in separate or distinct parts. + +Simple leaves may be Compound leaves may be + +Lanceolate. Trilobate. Lustrous. Bifurcate. Palmate. Trilobate. + +Ovate. Oblongate. Bipinnate. Bipinnate. + +Concave. Sagittate. Palmate. Trilobate. + +Linear. Eliptical. + +Spatulate. + +The Margin of Leaves may be— + +(1) Entire. +(2) Serrate. +(3) Biuncate. +(4) Concave. +(5) Denticulate (6) Dentate (7) Stipulate (8) Undulate (9) Scalloped (10) Acuminate. + +The Margin may be divided as— + +(1) Palmatifid. +(2) Fimbriated. +(3) Subdentate. +(4) Lobed. +Stipules may be leaf-like, or membranous, or both. They are found to be modified leaves; they protect the buds from injury. + +Erecta Leaves—These are found at the base of the flowers, and many form an involucre, cupule, or calyx. + +Fig. 10.—Transverse section of a bud of Symon. + +iv + +BOTANY FOR BEGINNERS +CH. IV + +Floral Leaves.---From these various parts of the flowers are formed. They can be divided into four kinds. +*Veration* or *Fruitation* is the folding of the leaves in the bud. + +QUESTIONS ON CHAPTER IV. + +(1) What is a leaf? Enthailing the leaves forming the flower, we have three kinds occupying different positions on the stem in the higher plants. +(a) (b) What parts are present in a perfect foliage leaf? (c) What kinds of veration are found in leaves? (d) What useful purposes may they serve in such cases? (1882.) +(2) (a) How many leaves are only imperfectly developed. What useful purposes may they serve in such cases? (1882.) +(b) Why is it that the leaves of the plant are called leaves? Is a stem? Why is it the most advantageous to the plant? (1881.) +(c) Describe, with examples, the simple form of compound leaves. What is the difference between a simple and a compound leaf? +(d) Explain, with examples, the following terms --- Insert, stipule, rachis, petiole, leaf-sheath, leaf-blade. +(3) What are stipules? Describe the stipules of the Rose and the Sweet Pea. +(4) How do the leaves of the Oak differ from the leaves of the Clover? (5) Describe, with examples, how a leaf-bud enlashing, the meaning of the term "veration." What is the usual position in which buds are developed on the stem? (1891.) + +50 + +CHAPTER V + +ANATOMY-STUDY OF ROOTS + +**Descending axis.** The descending axis, or root, is part of the plant which grows downwards, fixes it into the soil, and takes from the ground water in which minerals are dissolved. The root can be distinguished from the stem in the following way. + +ROOT. +1. The root produces neither leaves nor flowers. +2. The root as a rule grows downwards. +3. The growing point of a root is protected by a sheath which is called the **root cap**. +4. The root hairs, which absorb from the soil the water and minerals required by the plant for its growth. + +5. Roots grow away from the light. + +Exercises 35.—Dig up a Deadnutt and examine it. Note— +(i) The roots bear neither leaves nor buds. +(ii) The roots are very short. +(iii) The hair on the stems, which are close set and are used to protect the stem, is wanting. +(iv) The very minute and soft hairs on the roots. These can be best seen if the root be held up between the eye and the light and looked at through a hand-lens. + +k 2 + +STEM. +1. The stem produces both leaves and flowers. +2. The stem as a rule grows upwards. +3. The growing point of the stem is protected by scale-leaves. +4. The stem produces hairs ; but these are as a rule used for protection, and not for obtain- +ing food. + +Stems grow towards the light. + +A diagram showing the structure of a root and a stem. + +52 +BOTANY FOR BEGINNERS +CHAP. + +Exr. 36.--Take a few beans and soak them in water for twenty-four hours. With a sharp knife cut longitudinal slices from the middle, and place them on a glass slip, such as is used for microscope work, and examine under the microscope. The first section will appear clear. Move the sections first to the left, then to the right, and finally up and down. The dark hand-ends up to the eye. Move the sections first to the left, then to the right, and finally up and down. The dark portion is the growing point, and the lighter part the root-crop. +The **Primary Roots**.--The root produced by the elongation of the radicle is termed a primary root. When the primary root persists and continues to grow it is called a tap-root. In the bean, the Waterflower produce tap roots. Branches are produced from the primary root in regu- +lar order, and these branches are termed secondary roots, +base, i.e., near the apex or growing point. + +Fig. 20.--A Mapped section showing root-balls and secondary roots. + +The **Secondary Roots**.--The lateral branches of the primary roots are termed secondary roots. They differ from the branches of the stem in not being produced in an axial or horizontal line, but in an irregular order. Each plant produces a definite number of rows of rootslets, which are arranged longitudinally, the roots in each row being accurately one above the other. The secondary roots grow horizontally at first, but soon become vertical. The primary roots, and in this way is the roots between them parcel out soil. In the Waterflower there are four rows of roots, which strike out at right angles to each other. There is no space between them there is always uncrowded ground. This unoccupied ground is worked by roots produced from secondary roots. These secondary roots have no definite directions of growth, but spread outwardly, upwards, and in all directions, thus reaching every part of the vacant soil. + +Exr. 37.--Obtain a Waterflower plant with perfect roots. Wash the roots well and dry them thoroughly. +Examine the roots and observe-- + +(i) The primary root. +(ii) The secondary roots forming four rows. +(iii) The tertiary roots growing from the secondary roots. + +A diagram showing a mapped section of a plant with root-balls and secondary roots. + +V +ANATOMY--STUDY OF ROOTS +53 + +Exer. 38.--Compare the roots of the Dandelion, or any other plant which can be obtained, with the Wallflower, and note the number of roots of secondary roots. + +**Adventitious Roots.--The roots which are produced without the presence of former stems, leaves and roots are termed adventitious. In most monocotyledonous plants the primary root is either very short or ceases to grow soon after it has been formed. In many dicotyledonous plants a number of adventitious roots which spring from the stem. When gardeners place cuttings in the soil, they are said to "strike" when they + + +A plant with long, thin roots emerging from a stem. + +Fig. 71.--The glomerous root of a Grass. + + +A plant with numerous small, leaf-like structures growing from a stem. + +Fig. 72.--Branches of a Gooseberry bush producing adventitious roots. + +take root. This is brought about by adventitious roots being produced from the nodes of the stem which is pushed into the soil. + +**Clinging Roots.--When adventitious roots are used for climbing as in the Ivy, they are called climbing or clinging roots. Roots of this kind are very highly developed in many tropical plants like the Orchidaceae. + +54 +BOTANY FOR BEGINNERS +CHAP. + +Such roots simply cling to the bark of trees, they take nothing from the plant on which it grows. Some water plants produce a large number of roots which float in the water and help to support or moor the plant. The Duckweed, which grows in many of our ponds, is an example of this kind of root. + +Expt. 39.—Dig up a Grass plant from a field, and examine the roots. +Note: +(i) The tap-root is either absent or very short. +(ii) A large number of roots, which seem to come from each the top of the stem, are produced by the plant. These roots can easily be made out. They are called adventitious roots. They are also characteristic of the root system of the Water-lily. +Aerial Roots.—Adventitious roots which hang down in the air are called aerial roots. Epiphytes are plants which possess such aerial roots. The aerial root of some plants is covered with water-repellent wax, so that it does not lose its internal matter which may be blown away through the wind. Many Trees Ferns, Aroids, and Orchids are epiphytes. The Vine may, in some cases, produce aerial roots, but these are not so numerous as those of the Water-lily and most likely help to obtain water for the plant. Some aerial roots are green, and perform the same work as leaves. They may resemble leaves in shape and size. + +The Ivy clings to the bark of trees and old walls by means of aerial roots which are produced from the shady side of the stem. + +Water Roots.—The roots of plants which float or grow in water are known as water roots. They may be developed either from stems without leaves (as in the case of the Water-lily), or merged with leaves (as in the case of the Water-mint). Floating roots never penetrate even the mud at the bottom of a pond; but the roots of marsh plants go right down into the mud. The roots of Water-plantains, Water-alkes, and Elodea are found on both sides of the stem, and often extend into the bank into the water in which they float. Water roots do not produce root hairs. + +Expt. 40.—Hyacinth bulb, and place it in a vase of water. +Make up the loss of water which will take place by a solution 1 cone. +Formulae +Potassium nitrate $\frac{1}{2}$ gram +Sodium chloride $\frac{1}{2}$ gram +Calcium chloride $\frac{1}{2}$ gram +Magnesium sulphate $\frac{1}{2}$ gram + +Any student will make up this solution. + +V. ANATOMY--STUDY OF ROOTS 55 + +Such a solution contains everything necessary for the growth of a plant. Note how the bulb produces water roots, which obtain from the soil all that they need to grow into a healthy plant. Observe the growth of leaves and flowers. This experiment shows that roots, which under natural conditions live in soil, can change their mode of existence. + +EXPT. 47.--Cut a slip from any plant, (the garden Geranium will do), so as to leave at least three nodes with leaves and one without. Place the slip in a dish of water, and observe its development. + +Observe that roots develop in the water from the nodes. Keep the test-tube of water from being affected with scurf. These roots are adventitious and aquatic. + +Parasitic Roots.--The roots of those plants which pene- +trate a host plant, and extract nourishment from it, are called +parasitic. The Mistletoe, which grows on Apple, Fir, and + +R + +Fig. 73.--5th arm of Apple, S, shoot of Mistletoe; R, room of Mistletoe. + +Poplar trees in a parasite. Mistletoe is very plentiful in our homes about Christmas time, and most persons know its berries. +Thrushes feed on these berries, and the seeds enclosed in the +fruit are protected from the digestive juices by a hard covering. +They consequently pass out of the digestive tube without +undergoing any change; the droppings of the Thrush are + +56 +BOTANY FOR BEGINNERS +CHAP. + +generally voided from the upper branches of trees and carry the seeds with them. The droppings and the seeds which are enclosed in them cling to the branches. The seeds germinate and the radicle which is produced is pressed closed to the bark and remains there until it becomes a root. + +The Eye-bright, so common in fields, produces suckers on its root which attach themselves to the roots of grasses and extract nourishment from them. The Yellow-rattle, Loosewort, Cow-wheat, Toothwort, and Broom-Rape, are all parasites growing on the roots of plants. + +Expt. 42.--Pull up a few plants of Eye-bright and examine their roots. Find the suckers, which appear as little white knobs on the roots; they are always found on the secondary roots. + +Modified Roots.--Roots may be modified for the storing up of reserve materials, often becoming large and flabby, as in the + +Fig. 74.--Cinical root of Carrot. +Fig. 75.--Napiform root of Tump. + +Wheat, Toothwort, and Broom-Rape, are all parasites growing on the roots of plants. + +V +ANATOMY--STUDY OF ROOTS +57 + +case of the Turnip. Roots of this description belong to bionental plants. The principal shapes of modified roots are as follows: +1.—**Cylindrical**, when broad near the stem and tapering towards the apex, as in the Carrot (Fig. 74). +2.—**Nodiform**, when shaped like a Turnip. The Swede usually has, at the crown of the root, a seed from which the leaves sprout. +3.—**Fusiform**, when the root tapers both near the stem and towards the apex, e.g., Radish (Fig. 76). + +![Fig. 75.--Cylindrical root of Radish.](image) + +![Fig. 77.--Nodular or tubercular root of Pilewort.](image) + +4.—**Tubercular**, when the roots are swollen and round, as in the Pilewort (Fig. 77). + +EXPT. 43.—Obtain the roots of the Turnip, Carrot, and Radish. Make a sketch of each root, its shape, and mark on it the point where the reduction is size which you make. This can be done by measuring the size of the root with a ruler, and then drawing it to that size. A reduction can be found. The pupil should do this in all sketches made. + +EXPT. 44.—Dig up, either in March or April, the roots of the File- + +58 +BOTANY FOR BEGINNERS +CHAP. + +wort. This plant can be distinguished from the common Buttercup, because: +(i) Its leaves are conical and perfect, in the Buttercup the leaves are very much reduced. +(ii) The petals vary in number from eight to ten; in the Buttercup these are five, but in the Wort they are usually six. These petals are used for storing up nutritive materials. These are tubular leaves. + +Uses of Roots.--Roots perform various functions which can be arranged in a tabular form. +1. Roots fix the plant in the soil. The roots can anchor a tree like the Oak so that the strong wind cannot blow it over. +In many cases, such as in grasslands, the engineers, to bind together the soil along an embankment, and so keep it from falling, use on the West Coast of Lancashire and in other places. +2. Roots obtain nourishment from the soil. The roots parcel out the soil so that nutritive materials can be extracted from every part of the soil. In this way, the roots of a plant, like the leaves of a plant is obtained by the root-hairs from the soil. The soils make good the loss of water which takes place through the leaves. +3. Roots may be used as a store-house for material to enable the plant to produce flowers and seeds during the next season. In this case the roots are called storage roots. +4. Roots may be used for climbing, floating, or to enter a host plant. The shape, size, and method of growth of roots will depend upon their function. + +Every plant has its own growing-in a pot plant. Cover over the soil, either with card-board or tin-film, to prevent evaporation from the pot. Place the plant beneath a glass globe, and expose to light for at least two hours daily. Keep moistened with moisture. This is given out by the leaves, and the loss can only be made good by watering. + +Movements of Roots.--The younger portions of the roots are all in a constant state of motion. When the radicle leaves the seed it commences to move, and so long as life lasts the tips of the roots continue to move about in search of food or certain substances or conditions. The force exerted by a young radicle when growing is very great; in twenty-four hours it causes a downward pressure equal to lifting a weight of a + +ANATOMY--STUDY OF ROOTS + +quarter of a round. Roots not only move in the direction of least resistance, but also towards damp and away from dry soil. + +The use of these movements to the plant cannot be over- +estimated. If the root is placed so that its tip is through the soil in a perfectly straight line, not half of the food available for food would be touched; the spiral or circular movements of the root ensure its contact with the best sources of food in the soil. The tip of the root is always kept in constant motion, and the movement from side to side enables it to find the path along which there is least danger to the growing point. + +Experiments have been made by placing seeds on damp sawdust. When the radicle appears through the mycelium, turn the seed over so that the radicle points upwards. Under another radicle such as this, place a piece of paper tissue. Expt. 47.--Using the Beans or Peas germinated above, cut a small piece of root about 1 cm. in length so that it is above the growing point. Place this piece of root on one side of a tray of rice flour, and on the other side a piece of tissue paper. This can be done by using a solution of sodium chloride. + +Expt. 48.--Take from a few radicles, so as to remove a longitudinal layer from one side. Great care must be taken not to fix the cantal-fooi into the roots, as this will prevent them from moving and will not allow them to grow outwards. Make notes of the results. + +Expt. 49.--Put some sawdust in a box with a piece of glass. Fill up the box with alternating layers of sand, sawdust, clay, and peat. Sow some seeds of any quick-growing plants. Cover up all except one layer, and leave it until it dries out and warms up. +When the seed leaves are well up in the air, place the box on a window sill where they can receive light. Observe how the roots are placed against the glass. + +Expt. 50.--Plant some radicles in a pot of soil at 6 cm. apart, and nail on in place of the bottom a piece of wire netting with holes of about a quarter of an inch diameter. Put some water in the pot and keep it moist at all times. Remove all but two or three radicles at the bottom. Grow plants as in Expt. 48. Hang the box on a window sill and keep the soil moist. + +Note: The radicles grow through the wire netting. +(1) Many, if not all, will bend up and pass again into the box. This shows that they do not grow better than light. In fact, +nearly all roots grow away from light. + +SUMMARY. +Roots can be divided into-- + +Primary roots.--A primary root is produced when the radicle goes down. Thus, all primary roots are produced by the elongation of + +60 +BOTANY FOR BEGINNERS +CHAP. V + +rudules. Those roots which are formed from the primary roots are called secondary roots. When roots grow out of the secondary roots they are known as tertiary roots. + +Rudules. Those roots which are formed from the primary roots are called secondary roots. When roots grow out of the secondary roots they are known as tertiary roots. + +Rudules. Those roots which are formed from the primary roots are called secondary roots. When roots grow out of the secondary roots they are known as tertiary roots. + +Rudules. Those roots which are formed from the primary roots are called secondary roots. When roots grow out of the secondary roots they are known as tertiary roots. + +Rudules. Those roots which are formed from the primary roots are called secondary roots. When roots grow out of the secondary roots they are known as tertiary roots. + +Rudules. Those roots which are formed from the primary roots are called secondary roots. When roots grow out of the secondary roots they are known as tertiary roots. + +Rudules. Those roots which are formed from the primary roots are called secondary roots. When roots grow out of the secondary roots they are known as tertiary roots. + +Rudules. Those roots which are formed from the primary roots are called secondary roots. When roots grow out of the secondary roots they are known as tertiary roots. + +Rudules. Those roots which are formed from the primary roots are called secondary roots. When roots grow out of the secondary roots they are known as tertiary roots. + +Rudules. Those roots which are formed from the primary roots are called secondary roots. When roots grow out of the secondary roots they are known as tertiary roots. + +Rudules. Those roots which are formed from the primary roots are called secondary roots. When roots grow out of the secondary roots they are known as tertiary roots. + +Rudules. Those roots which are formed from the primary roots are called secondary roots. When roots grow out of the secondary roots they are known as tertiary roots. + +Rudules. Those roots which are formed from the primary roots are called secondary roots. When roots grow out of the secondary roots they are known as tertiary roots. + +Rudules. Those roots which are formed from the primary roots are called secondary roots. When roots grow out of the secondary roots they are known as tertiary roots. + +Rudules. Those roots which are formed from the primary roots are called secondary Roots +Rudules. Those root +Rudules. Those root +Rudules. Those root +Rudules. Those root +Rudules. Those root +A diagram illustrating how to cut sections of a plant. +Fig. 81. + +62 +BOTANY FOR BEGINNERS +CHAP. + +large flat sections a cutting instrument with a flat side must be used. The section when made may be so thin that light can + +A transverse section, cut through A, B, C. +B A radial section, cut through A, B, C. +C A tangential section, cut through A, B, C. + +Expt. 50.--Take a kidney potato and cut sections from it; they will be made in three directions, as fol- +lows. Sections parallel to the long axis (A) will be a transverse section. +Sections parallel to the long axis, and passing through the centre (B) will be a longitudinal section. +Sections perpendicular to the long axis, but not passing through the centre; this will be a +mounting Specimens. After the sections have been cut they must be mounted on ordinary microscopic slides, 3 inches long by one wide. All fresh specimens can be mounted in water and examined without difficulty. For examination by a hand lens the dry object can often be used. Great care must be taken that both sides of the object are perfectly clean, for the slightest amount of dirt will spoil the section. In mounting the object in fluid only a small drop of it should be used, just sufficient + +Fig. 50.--Transverse section through a square stem. + +VI HOW TO PREPARE AND EXAMINE SECTIONS 63 + +to cover the object. For examination under the microscope, the section must be covered with a cover-glass; these can be obtained of different sizes, the one in general use being $4$ of an inch in diameter. + +If the section from which the sections have to be prepared has been kept in spirits, they must be mounted either in alcohol or glycerine. The section must never be allowed to dry; if it does, it will become brittle and break easily, so as to make the specimen appear very dark. + +(1) Do not begin to cut sections until you are quite certain what kind of material you are going to examine. With a compound microscope, keep the razor or knife wet by dipping it before each cut into a glass of water for fresh specimens, and in spirits for materials which are difficult to cut. + +(2) Keep the microscope perfectly clean, and be careful that no obstruction is placed between the objective and the front of the instrument. + +(3) When measuring the specimen, only just sufficient of the surrounding medium must be used to cover the object. When the cover-glass is put on, it should be held at right angles to the slide, and while touching the mounting fluid and be slowly lowered into position, so as to equalize its weight with that of the slide. This is best done by using a needle or pin to support the cover-glass, with the thumb and finger of the left hand guide it into position as the needle or pin is withdrawn. + +(4) Always keep the section wet so as to avoid air-bubbles. If air-bubbles occur, they may be removed by gently warming the side by placing it over a fire or containing hot water. When this has been done, place a piece of paper on top of it, and write on this label the name of plant, portion of plant, direction of section, etc., and also any other information that may be necessary. + +Expt. 51—Take a glass slide, and with a dipping rod place a single drop of water in the centre. Now place a cover-glass over the drop of water, and press down gently with your thumb and finger of the left hand guide the cover-glass into position. As you do this slowly withdrawing the needle or pin. After a few attempts this operation will become easy for you so as to fill the entire space beneath the cover-glass. + +The Structure and use of a Hand Lens.—A lens is a transparent body made of glass or some other material shaped so as to change the direction of the rays of light which pass through it. A lens appears to magnify or diminish the size of objects seen through it. A hand-lens is a piece of glass, suitably mounted which possesses the property of magnifying objects. + +64 +BOTANY FOR BEGINNERS +CHAP. + +One of the best and cheapest for botanical work is shown in Fig. 83. It is called a triplet, because there are three lenses mounted so that each one can be used by itself, or in combina- +tion with the others. To use such a lens to view a transparent object (as a leaf, a flower, etc.), place the object on the table in front of the specimen until it appears bright and clear. The object is said to be in focus when it is best seen. In the specimen case, the object may be moved back and forth, or up and down, to move both the lens and object until a good view is obtained. +Transparent objects can be seen best with all the three lenses as + +Fig. 83.--Diagram illus- +trating how power is +changed by moving +the highest power lens +up or down when it is +needed. + +Fig. 84.--Diagram illus- +trating position of +highest power lens when +it is needed. + +Fig. 85.--Diagram illus- +trating position of +highest power lens when +it is needed. + +shown in Fig. 84, but if the objects are opaque, with either lenses +or 2, or 3 and 2 combined, as in Fig. 85. In Fig. 86, the edges of the leaves A, B, and C indicate the relative distances at which a specimen may be viewed by 1, 2, +and 1 and 2, 3, respectively. + +Expt. 33.--Place a little cotton wool between two microscope slides, and cover them with a piece of glass. If this glass is thin enough, it can be held so as to focus it with (i) the lower power, (ii) the medium power, (iii) the highest power. + +VI HOW TO PREPARE AND EXAMINE SECTIONS 65 + +**Cells:** If a thin transverse section of the stem of the sunflower be made, and examined with a hand-lens, a number of openings will be seen; these represent the elementary parts of the plant, and are called cells. The portion of the cell which surrounds the protoplasm is termed the **cell wall**, and in such a section is the most prominent part of the cell. The soft material receives the name of **protoplast**, and is the most important constituent of the cell. The protoplasts are surrounded by cell-walls, and these are arranged to form definite structures, which receive the name of **tissues**. + +**EXPT. 53.—Obtain a ripe tomato and mount a small portion of its stem in water. Examine under a hand-lens. Observe that the cells are very large and oval, the cell-walls are very thin, and a thin protoplasmic layer is present between them.** + +**EXPT. 54.—Sow some seeds of the Sunflower in soil, and when the stem is about six inches in length, cut transverse sections of it in a strong solution of potassium permanganate, and wash out the alcohol to clear them. Mount the thinnest section in glycerine and examine under a hand-lens. You will see that it is large and filled with protoplasm, and are arranged in definite groups.** + +**EXPT. 55.—From a small Beetroot cut a thin transverse section, and mount it in water. Examine under a hand-lens. Observe that the cells are filled with colourless cytoplasm. Place this section in alcohol for twenty-four hours, and then mount again; you will have noticed out. This is due to the sap being killed while the protoplasm was still living.** + +**EXPT. 56.—Cut a thin section from a Potato, mount and hold it in water for twenty-four hours, then mount again (see fig. 87). Examine with a hand-lens. Note the cells appear as many bodies, but they are not separated into definite groups.** + +**Tissue:** A transverse section of the stem of a Sunflower be made and examined (see fig. 87); the cells are seen to be arranged in a certain definite manner. On the outside is a single layer of cells, which are known as the **epidermis**. In all cases the cells which cover the plant, and protect the deeper parts from moisture, are known as **epidermal tissue**. Within this section a number of cells can be seen which form a ring-like structure; these are separated from the epidermis by a layer of cells. This ring of cells forms the **vascular tissue** of the plant. The separate groups of cells are called **vascular bundles**. In the centre, and between the vascular ring and the epidermis, + +F + +66 +BOTANY FOR BEGINNERS +CHAP. + +number of cells can be seen. These fill up the interspaces, and can be called packing cells, or ground tissue. +All the higher plants are built up of tissues. These tissues consist of cells which are grouped together to perform special work. The three kinds of tissues found in the stem of the Sunflower are also found in leaves, roots, and flowers. + +Exr. 57.--If a young shoot of a Holly Tree be searched during the summer for a number of leaves in va- +rious stages of growth, one may find with ease a leaf which will be found to be composed entirely of ground tissue. This is found with the veins, but not with the leaf blade itself. The veins are made up of the leaf tissue, and have received some material, and have retained a little of the atmosphere (a), so that they are not so dry as the other parts of the leaf. + +Fig. 17.--Transverse section of stem of Sunflower. +A, epidermis; B, cortex; C, vascular ring. (1-3) + +Exr. 58.--Obtain an old Cabbage-stalk and cut a transverse section through it, as shown in Fig. 89. Examine it with the aid of a hand-lens, and note the following: + +(1) The epidermis, this is shown at A, Fig. 89. + +(2) At A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z is the outer surface of the stem, see Fig. 80q and the epidermis; this is made up of vascular cells (1). + +(3) In the cortex (B), there is a number of cavities in c) this is the pith. Between the epidermis and the vascular cylinder is a layer of ground tissue which it called the cortex. These cells form the ground tissue of the plant. + +(iv) On the outside of the stalk is seen a number of munks. + +66 +CHAP. + +A diagram showing different layers of a plant stem. +A: Epidermis +B: Cortex +C: Vascular ring + +Exr. 57.--If a young shoot of a Holly Tree be searched during the summer for a number of leaves in various stages of growth, one may find with ease a leaf which will be found to be composed entirely of ground tissue. This is found with the veins, but not with the leaf blade itself. The veins are made up of the leaf tissue, and have received some material, and have retained a little of the atmosphere (a), so that they are not so dry as the other parts of the leaf. + +Fig. 17.--Transverse section of stem of Sunflower. +A: Epidermis +B: Cortex +C: Vascular ring. (1-3) + +Exr. 58.--Obtain an old Cabbage-stalk and cut a transverse section through it, as shown in Fig. 89. Examine it with the aid of a hand-lens, and note the following: + +(1) The epidermis, this is shown at A, Fig. 89. + +(2) At A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W, X, Y, Z is the outer surface of the stem, see Fig. 80q and the epidermis; this is made up of vascular cells (1). + +(3) In the cortex (B), there is a number of cavities in c) this is the pith. Between the epidermis and the vascular cylinder is a layer of ground tissue which it called the cortex. These cells form the ground tissue of the plant. + +(iv) On the outside of the stalk is seen a number of munks. + +66 +CHAP. + +VT HOW TO PREPARE AND EXAMINE SECTIONS 67 + +These are the places where the leaves were inserted; they are called leaf axils. + +EXPT. 55.--Cut a transverse section of a twig of the Limes tree. +Note--that the wood is made up of a number of rings. Each ring consists of a layer of cells which have been formed during one year's growth. These are shown in Fig. 90. Each ring represents the amount of growth that has taken place during one year's time. The age of the tree can be told by the number of rings of wood present. + +A diagram showing a transverse section of a twig of the Lime tree. +Fig. 89.--Shedder leaf of Holly. +(trifoliate, simple, deciduous) + +EXPT. 60.--Cut in autumn a longitudinal section of the stem of the Honeysuckle (Lonicera) through the base of a leaf. Examine such a section with a hand-lens. +Note.--(1) The base of the leaf is connected with the stem (see A, Fig. 91). +(2) The base of the leaf is surrounded by a sheath-like cover (see B, Fig. 91) the base of the leaf. This layer, when the leaf has performed all its work, separates from the stem and covers up the base of the leaf. + +EXPT. 61.--Cut a transverse section of the stem of the Maize, and examine it under a hand-lens. Put it into alcohol so much the better, because there will be a smaller number of air bubbles present, and the section will be far clearer. Examine with the low power first, and then with the high power. +(i) The primary cortex. This surrounds the vascular bundles and helps to support the plant in an erect position. + +12 + +68 +BOTANY FOR BEGINNERS +CHAP. + +(iii) The ground tissue; which separates the vascular bundles, and in which only one layer of cells is found. +(ii) The vascular bundles which are scattered; they are not arranged in the form of a ring as in the Monocotyledons, but are scattered, and most numerous near the primary cortex, and largest and few in number near the endodermis. +All plants with scattered vascular + +A circular cross-section of a plant stem, showing the different layers. +Fig. 90.--A piece of the stem of a plant showing the different rings. + +K B A +B, cork layer (X 5) +Fig. 91.--Longitudinal section of stem of plant of fig. 90. + +The bundles belong to the Monocotyledons, and those with the bundles arranged in a ring to the Dicotyledons. + +A longitudinal section of a plant stem, showing leaf stalks and buds in the axils of leaves. (x 2) +Fig. 92.--Longitudinal section of stem of Syzygium, showing leaf stalk and buds in the axils of leaves. (x 2) + +Expt. 6a.--Select an old root of the Maize from which a number of roots are growing. Cut off a piece about an inch long to pass through one of the young roots. Select one of the thinnest and moist in water or glycerine. Examine with hand-lens. Note: +(i) The young root which is found on one side of the section. +(Fig. 93.) K.) + +68 + +VI HOW TO PREPARE AND EXAMINE SECTIONS 69 + +(ii) The way the scutellum springs from close up to the vascular bundles, and breaks through the cortex and epidermis. + +Expt. 63.—Dig up two rhizomes of the Sweet Flag (Acorus). In autumn, in the woods near Llanfair, Youghal, County Cork, Sussex, and in Scotland and Ireland. + +Select a young one and cut transversely. Observe how this section is formed, and mount it in glycerine. Examine, and note— + +(i) The scattered vascular bundles (Fig. 50). + +(ii) The vascular cylinder formed by the numerous vascular bundles. + +R + +Fig. 50.—Transverse section of the root of Maize. R, roots. (x 12.) + +Fig. 51.—Transverse section of the rhizome of the Sweet Flag. (x 4.) + +(iii) A few roots which spring from close up to the vascular bundles may also be seen in Fig. 94 they can be seen breaking their way through the cortex. + +Expt. 64.—From a stem of the Vetch (Vicia), make transverse sections. Select a thin one from these and mount it in water. Examine— + +(i) The pith (which may have dropped out) + +(ii) The vascular bundles in which the cells are arranged. + +(iv) The epidermis which presents a sinuous outline. + +Expt. 65.—Make a thin transverse section of a shoot of the Pine which has been kept in alcohol for some time. Mount in glycerine, and examine. + +(1) The cells; these are small and close together (Fig. 97) in one part of the section, but large in the remaining portion. + +(2) The small thick walled cells are formed in late summer and autumn. + +Pine shoot + +Fig. 52.—Transverse section of stem of pine. Note that middle part of section has dropped out. (x 2.) + +70 +BOTANY FOR BEGINNERS +CHAP. + +the larger ones in spring and early summer. The small cells are dark coloured; these form the dark portion of the annual ring. The large cells are light coloured and form the lighter coloured portion of the annual ring. + +EXTR. 66.--Cut a radial longitudinal section through a young stem of the Pine (Fig. 95). + +(1) The cells are cut through longitudinally (Fig. 96), and some of them show a pitted arrangement. + +(2) The walls of the cell will seem to cross the section in different parts; these are the walls of cells which are cut across transversely. + +EXTR. 67.--Prepare a transverse section of a young root of the Pine, which has been kept in water for some time. This root should not + +Fig. 95.--Radial section +of stem of Pine. +Fig. 96.--Transverse sec- +tion of stem of Pine. +(x 3). +Fig. 97.--Transverse sec- +tion of root of Pine. +(x 3). + +be above 1 cm in diameter. Mount in glycercine. Examine with a hand-lens. Note: + +(1) Around the base part a series of cells which are arranged in regular rows; these are cork cells, and form the protecting tissue of the root. + +(2) A number of annual rings which have the same appearance as those seen in the stem (Fig. 98). + +EXTR. 68.--Make a number of transverse sections through the stem of the Rose on which prickles are found. Select a thin section which passes through one of the prickles. + +If this is examined by the aid of a hand-lens, the prickle will be seen to arise from the epidermis (Fig. 99), but also from a portion of the cortex. + +EXTR. 69.--Obtain a leaf of the Rhododendron, and bleach it by placing it in a solution of sodium hypochlorite (bleach). This can be done by placing the leaf between slices of Potato, carrot, or Ethers, and immersing it in a solution of sodium hypochlorite (bleach). The soaking substance as to pass through the leaf, a number of sections will be obtained. Place these in water or alcohol in a watch-glass, and + +VI HOW TO PREPARE AND EXAMINE SECTIONS 71 + +pick out the thinnest. Mount to glycercine. Examine with the high power of the hand-lens. Note— + +(i) The size of the section and its permanent part of the section. In the centre of this a vascular bundle will be seen. + +(ii) The epidermis which covers the whole surface of the section. + +(iii) The ground tissue which comes between the epidermis and the vascular bundles. + +How to Use a Compound Microscope + +The following is a set of rules to direct the student in the use of a compound microscope. + +(i) Before commencing to use the micro- +scope it must be examined to see if it is per- +fectly clean. If it is not, the student should +regard his own way on to the stage, clean +them off at once with a soft clean cloth. +(ii) The objective and eyepiece must be +directed up through the tube by the mirror. +(iii) When examining a slide, all dust and +dust must be removed from the slide. If they +are on the glass, they may be removed by +the cleaned off with a soft silk rag. If they +are on the cover-glass, they may be removed +by rubbing them off with a piece of paper. +(iv) The objective, which must be kept +clean in the same way. If either glycercine or Canada balsam is smeared on to it, it must be washed off and +directed on to it from a wash-bottle and then be carefully dried. Canada balsam is removed easily by alcohol or benzol. +(v) To adjust the focus, turn the screw on the low power objective, and move the mirror until the whole field is illuminated. + +Fig. 99. Transverse section of leaf of Rhododendron. (× 63) + +Then turn the tube down until it nearly touches the slide ; if the tube is now racked up very slightly, a good view will be obtained. In most cases a good view can be obtained with a low power without using any fine adjustment, but if there is any difficulty the fine adjust- +ment can be used. + +A stylized illustration of a plant with leaves and stems. +A stylized illustration of a plant with leaves and stems. +A stylized illustration of a plant with leaves and stems. +A stylized illustration of a plant with leaves and stems. + +72 +BOTANY FOR BEGINNERS +CHAP. + +With a high power the method of focusing the scope is the same, only greater care is required. If the objective is used, it can be racked down until the image of the objective appears to meet the objective. The slide is then moved so that the object is in line with the rack and away from the slide it will come into view, and with the finer adjustment of focus the object will be brought into clear view. + +The pupil must on no account rush the tube towards the object at the time when he first looks through it, for if this is done, either the tube is misled and the objective may be forced through the slide, or the section may in this way be damaged and the lens ruined. The section should be laid on a glass plate, and then held by one hand while looking down the tube, rack it away until the object becomes clear. The tube should then be slowly racked back again, and after all possible detail has been made out with this, the high power can be used. + +(a) A high power must never be used unless the object is covered with a thin glass. This prevents the microscope from touching the section. (b) Drawings should always be made of objects under magnification. This practice compels attention to details, and tends to produce the habit of close observation. In drawing, a fine pointed pencil should be used, and the paper should be clean white paper or Bristol board. The drawings should always be made to scale. + +SUMMARY. +Sections of a plan can be made in three directions. If the section of the nerve passes right through it is said to be a transverse section. When the section is made in the direction of the long axis of a body, it is called a longitudinal section. If sections pass through both stem and leaf, it is said to be a tangential section. + +Mounting Specimens—Fresh specimens can be mounted in water, and mounted slides can be made from them. Dried specimens must either alcohol or glycerine. Sections must be kept wet to prevent air bubbles from forming between them and their cover-glass. + +1 + +**Hans-Lenz**—A hand-lens is a piece of glass which possesses the property of magnifying objects, and is mounted in wood, horn, or metal for portability. It is usually convex in shape and has a hole near its edge to let the eye and to bring the object into such a position that it can be seen clearly. Cell Slants are built up of elements which receive the name of cells. A cell is surrounded with a cell-wall, and contains protoplasm. Protoplasm consists of a number of cells. There are three kinds of tissues; they are— + +Cell wall; + +Protoplasm; + +Vascular tissue; + +Ground tissue; + +VI HOW TO PREPARE AND EXAMINE SECTIONS 73 + +The Compound Microscope is an instrument which consists of lens and accessory parts. Such an instrument is used for the examination of the minute parts of plants. + +QUESTIONS ON CHAPTER VI. + +(1) What do you understand by the term "section"? What kinds of sections can be made? + +(2) Write a set of rules to guide you in mounting sections. + +(3) How many lenses are there in a compound microscope? What glass is placed over the objective, and how is such a cover glass put on ? + +(4) Explain what is meant by air-bubbles, and how they find their way into a section. + +(5) A hand-lens and a transparent section are given to you. How should you proceed to examine them? + +(6) What is a cell? Of what parts does a cell consist ? + +(7) Draw a diagram showing the structure of a plant cell, showing the cells. Explain how you would proceed to do this. + +(8) What is meant by the term "tissue." What kinds of tissue can be found in plants? + +(9) What is meant by the stem of the Sunflower, and compare it with the stem of the Maize. + +(10) Explain the term annular ring, as applied to woody trees. How would you distinguish between a ring formed by the cambium layer and one formed by the phloem layer ? + +CHAPTER VII + +THE HISTOLOGY OF THE CELL + +The Cell—All parts of plants agree in being built up of microscopic elements which have received the name of cells (p. 65). The cells which are alive are called living cells, and those which may be living or dead. Dead cells perform an important func- +tion in giving firmness and rigidity to the plant. They may +also serve as a storehouse of food materials, and protect +deeper parts of the plant from injury. Cells may be separate, +as in the ripe pulp of the Tomato, but in most cases they are +all united into a mass, which is known as tissue. The kind of +development, and upon this will depend the kinds of tissue +which they may produce. It will be an advantage to begin by +studying the structure of a cell. + +The Structure of a Cell—As living cells change with +age it will be better to take a young cell and to follow it until it +becomes mature. +In a young cell, such as can be seen in the cortical (p. +30) layer of the stem of most plants, the following +constituents can be distinguished. On +the outside is a mem- +brane separates the cell from others which surround it, +and is called a cell-wall. In close contact with the whole surface +of the cell wall lining the entire cavity of the cell, is the +protoplastin. Embodied in the protoplast is a denser, +granular portion which is called the nucleus. + + +A diagram showing the structure of a cell. The outermost layer is a membrane, followed by a cell wall, then a layer of protoplasm, and finally a nucleus. + + +Figs. 178.—The leek-bud figure, a young mesophyll +cell of a leaf; N, nucleus; NL, nucleolus; V, vacuole; +N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., +nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; +N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., +nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; +N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., +nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; +N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., +nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; +N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., +nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; +N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., +nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; +N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., +nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; +N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., +nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; +N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., +nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; +N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., +nucleolus; N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; +N.L., nucleolus; N.L., nucleolus; N.L., nucleolus; + + +CH. VII +THE HISTOLOGY OF THE CELL. +75 + +Formation and Growth of the Cell-Wall.—The cell-wall is very strong and elastic, and is formed from and by the proto- +plasm, and its increase in thickness and area depends upon the rise of tension within the protoplasm. The increase in area +owing to the stretching caused by the pressure set up inside the cell, but throughout this increase in size new material is deposited on the surface, some cases the stretched cell- +wall breaks, and the ruptured edges separate. The break is completed by separation of the subsequent growth of the cell- +wall by the deposition of new material which connects the disintegrated parts. + +The cell-wall grows in thick- +ness by the deposition of suc- +cessive layers on the inner +surface of the first-formed layer. +This kind of growth is termed +primary growth. After the subse- +quent growth of the cell- +wall by the deposition of new +material is completed, a layer is +called growth by intussuscep- +tion. As a general rule growth +of the cell-wall takes place only +until after a cell has reached its full size. When such a cell-wall is examined by the high power of the microscope, it exhibits a +striated appearance; this is owing to the constituent layers acting as lamellae. In many cases, however, cells, which are found on cell-walls are due to the unequal deposition of the new +material during growth in one part of the spiral, annular, and pit-plate-like compound which are found in the wood of most +plants, are caused by this unequal growth. + +The Chemical Composition of the Cell Wall. If a few drops of dilute acid are added to a cell-wall they assume a yellow colour, and the further addition of a single drop of +1% sodium-is made by dissolving crystals of potassium iodide in distilled water until it becomes slightly turbid. This solution is then added to a drop of +the cell-wall solution and shaken well. The iodine combines with any starch present in the wall, giving a blue-black precipitate. This alkaline solution is made in the same way, only alcohol is used instead of water. + + + + + + + + + + + + + + + + +
abc
Fig. 30.Cell with thickened wall.Fig. 31.
Cell with pitted transverse wall. (× 200.) (b)Cell with pitted transverse wall. (× 200.) (c)
+ +76 +BOTANY FOR BEGINNERS +CHAP. + +strong sulphuric acid causes the yellow colour to be replaced by a deep blue. +This reaction is characteristic of a substance termed cellulose. +We may consequently conclude that the cell-wall consists primarily of cellulose, which is composed of three chemical elements, known as carbon, hydrogen, and oxygen. +All organic bodies which have the hydrogen and oxygen combined with carbon in the proportions necessary to form water are grouped together as carbohydrates. +The proportion by weight in which carbon, hydrogen, and oxygen are present in cellulose is represented by the following percentage composition: + + + + + + + + + + + + + +
Carbon44.44
Hydrogen6.17
Oxygen49.38
+ +99.99 (= 100 very nearly). + +From this it will be seen that there is eight times as much oxygen as hydrogen by weight in cellulose. +But water is made up of eight parts by weight of oxygen to one of hydrogen. From the following analysis we see: + + + + + + + + + + + + + +
Hydrogen11.35
Oxygen88.64
Total100.00
+ +Hence, we are justified in classing cellulose as a Carbo- +hydrate. +Mineral substances such as silica, carbonate of lime, and oxides of iron are also found deposited in cell-walls. +Chemical Changes which the Cell-wall may under-go.--- +1. A portion, or all, of the cell-wall may become cuti- +cellularised, either by the deposition of cutin on the +cellulose, or by the deposition of cutin in the cell-wall. +The epidermal cells of some leaves afford a good example of this change. The outer layers of the leaf-stalks are touched with iodine and sulphuric acid, some of the layers of the wall of the epidermal cells will assume a deep blue colour; the colour is deepest in the inner layers, the outer layers not + +VII THE HISTOLOGY OF THE CELL 77 + +showing it at all. The external layer of the epidermal cells is called cuticle, which is almost impermeable to water. + +The walls of corky cells have the same properties as cuti- +cularised cell-walls, and they give the same reaction with iodine. +They are also impervious to water and to alcohol. Both +cutin and suberin contain about 74 per cent of Carbon. + +2.—The cellulose of the cell-wall may, owing to the deposition of lignin, become yellowish-brown in colour. This yellow colour gives a blue colour when treated with aniline chloride and hydro- +chloric acid. Lignification, while it makes the cell-wall harder and more resistant to mechanical injury, does not prevent it readily traverse it. Lignification takes place most largely in woody tissue, and to a less extent in other parts of the plant. + +3.—The outermost cell-wall may be thin or thick, or less +mucilageinous. This change is caused by the conversion of +cellulose into mucilage, which may be either a form of cellulose +or a form of gum. + +Exr. 70.—Obtain a small quantity of Sprigyna, which is found in +the soil near the roots of many plants. Mount some of it in water, and examine it under a low power of the microscope. Note— + +(i) That the cells are long and narrow. + +(ii) That each cell contains protoplasts. + +(iii) That the protoplasts are greenish-yellow. + +Place a small quantity of Sprigyna in a watch glass and cover it with water. Place this on the stage and examine it first with a low power, then with a high power. Note— + +(i) The cell-walls are slightly stained yellow. + +(ii) The protoplasts are greenish-yellow. + +(iii) The nucleus is still more deeply stained than the protoplasts. + +Exr. 71.—Take a piece of cork, scrape away its outer coat, +Cut out a small piece of the inner material (wax-like substance) stored up in the seed. This can be done by using either the heel of the hand or a straight edge. Mount this in water and examine it under a low power and then under a high power. Note— + +(i) That the cells are long and narrow. + +(ii) That each cell contains protoplasts. + +(iii) That the protoplasts are greenish-yellow. + +(iv) That the membrane which closes these pits is called the closing membrane. It is sometimes called the closing wall. + +(v) That the closing membrane is sometimes called the middle lamella (Fig. 102). + +(vi) Sow a section for a few minutes in iodine, and mount in glycerine. Note— + +(vii) Another similar section which has been soaked in iodine and a drop of strong sulphuric acid. Examine it under a low power only. +Observe how the cell-walls swell, how their shape alters, and assume + +78 +BOTANY FOR BEGINNERS +CHAP. +a blue colour. (See that no sulphuric acid finds its way on to the microscope.) +EXPT. 72.--Take some cotton wool and first soak it in alcohol for half an hour to drive out the water. Mount it in water. Examine it first under a low power, then under a high power. +(i) The twisted filaments, which consist of single cells. +(ii) The remains of the protoplast seen clinging to the interior of the cell. +(iii) Treat a small quantity with iodine solution--the walls stain slightly yellow. +(iv) Add a drop of strong sulphuric acid after the cover-glass has been removed, when a distinct blue colour will be seen. +Evidently cotton consists principally of cellulose. + +Fig. 105.--Section of endosperm. +Fig. 106.--Cotton showing pits. + +EXPT. 73.--Cut sections from a cork and soak them in alcohol. Mount the thinnest in water and examine with the microscope. +Observe: +(i) The cell-walls, which have a clear outline. The cells have lost their contents. +(ii) In another section with iodine solution, the walls stain yellow. +(iii) Treat another section with iodine and sulphuric acid; the walls still yellow, but the cells; neither do they swell with sulphuric acid, but keep their outline. + +EXPT. 74.--Cut sections from a wooden match and soak them in alcohol. Mount the thinnest in water and examine with the microscope. Observe the cell-walls, which are seen to have a number of pits (Fig. 105). To test this: +(i) Treat another section with iodine and sulphuric acid; it swells and becomes transparent. +Nor.--A cellulose blob can thus be distinguished from a lignified or a corky wall because it gives a blue colour with iodine and sulphuric + +Figs. 105.--Section of endosperm +Figs. 106.--Cotton showing pits + +THE HISTOLOGY OF THE CELL. +VII + +acid. A gelatinised wall is stained brown and swells, and a corky wall is stained brown but does not swell. + +Expt. 75.—Soak some Linseed in water, and note how they swell and become gelatinised; the seed, which are hard and horny, have been converted into mucilage. + +Make a section from a dry seed and moist in glycercine and water. Knock off the excess of liquid with blotting paper, and observe the strata on it become very clear. + +The Protoplast. The protoplasm is the living and active part of the cell, and is a semi-liquid material, which has embedded in it a number of granules, and is kept moist by the cell-sap, which saturates the whole of the cell. + +In a living cell the protoplasm consists of a number of fibres which cross in all directions to form a net-work, the meshes of which are filled in with a more fluid substance. + +In a dead cell these fibres are no longer connected with the cell-wall; but if the temperature of the cells be raised to 120° F., the protoplast coagulates, i.e., sets like the white of an egg, and becomes solid, and then loses its power of movement and dies. Alcohol or weak acids produce similar results. + +The Composition of Protoplastam.—If a few cells are treated with iodine, they will turn blue-black. This is the same colour which the substances called protides give with iodine, and it seems very probable that protoplasm is built up of protides. + +A protid is a substance which contains Carbon, Hydrogen, Oxygen, Nitrogen, and Sulphur. The essential element of a protid is nitrogen, and this is found in every protid, though in different places of protid. The proportion of the above elements in living protoplasms varies according to their nature. In order to kill it in the process, and there may be a difference between the composition of living and dead protoplasms. Protoplasts contain either carbonic acid or carbonic oxide gas. These gases are wonder- ful substances in universe, because life is never found apart from it. They are necessary for the existence of all living things, plants and that of animals. + +The Movement of Protoplastam.—The protoplastam of a plant possesses the power of movements. These movements can be observed in large cells with thin and transparent walls, especially when the colourless protoplastam contains a large number of granules. These granules are driven backwards and forwards with the stream, and they appear much as particles of + +80 +BOTANY FOR BEGINNERS +CHA. + +mod would do in a swiftly moving river. When the granules in their movements go round and round, and the interior of the cell, the movement is called rotation. +In an old cell where the protoplasm does not completely fill the interior, and where the vacuoles are empty, the granules are filled with cell-sap. The connection between the protoplasm in different parts of the cell is kept up by strands proceeding from one part to another. These strands move up and down another, much as the blood corpuscles move in the blood stream. This latter movement, which is more complex than that of rotation is called circulation. The individu-als of a species differ in this respect. Those which have unequal rapidity, according to their sizes, the smallest moving fastest. +The currents in the protoplasm are apparently irregular, now advancing, now retreating, sometimes suddenly arrested, and commencing again with increased rapidity. The movements depend on temperature. In winter they are slow and summer, during dry weather, they are arrested. In spring, when there is plenty of moisture and a fair amount of heat, they are seen at their best. + +EXPT. 76.—Obtain a plant of the American Water Wort (Eloasia) and place it in a glass of water. Place a cover-glass on, and examine with a high power. Notice: +(1) The protoplasm in the protoplasm. +(2) The movement of the granules; they move round and round— +the same way. +(3) Gently warm the slide over hot water. Examine again. The movements are arrested. +(4) Now hold the side either over a gas flame or a spirit lamp until the water boils. Examine again. There is no movement, the protoplasm has been killed. + +EXPT. 77.—Remove a portion of the epidermis of a Stinging Nettle and mount it in water; examine with the low power. Notice: +(1) The epidermis is very thin; it is only about one-hundredth of a power, observe— +(2) It is wider at the base than at the apex of the hair; +examine the protoplasm, vacuoles, and cell-wall. +(3) The protoplasm moves up one strand and down another—this is circulation. + +EXPT. 78.—Remove a small portion from near the core of an American Apple. Mount in water and examine under a low power; focus a cell + +THE HISTOLOGY OF THE CELL + +8r. + +near the centre of the field and proceeds to observe a single cell with the high power. Make out— + +(i) The cell-wall, protoplasm, nucleus, and vacuoles. +(ii) The position of the protoplasm in relation to the protoplast is stained brown, and the nucleus a very dark brown. +(iii) The position of the protoplasm in a specimen with salt solution (1 per cent.). +(iv) The wall retains its original position and appearance, but the protoplasm contracts and becomes more or less transparent. +(vi) Wash out the salt solution with water and examine again ; the protoplasm will be found to have returned to its original position. +The contraction of the protoplasm is due to the salt solution attracting the water from the cell ; and it regains its original position when water again is taken up by the cell. + +The protoplasm is stained a deeper colour than the protoplast ; +it stains a deeper colour when treated with iodine solution. In shape the nucleus is somewhat oval and in its interior there are numerous vacuoles which may be seen. +It is built up of protoplasm, and contains a large quantity of phosphorus. A nucleus is present in all cells, and this seems to be necessary for life, as it is destroyed during death of the cell. It is always formed from a preceding nucleus. +The exact function of the nucleus is not known, but in every case of cellular life it has been observed that it is essential for life. It has been suggested that the nucleus is the most important part of the cell, and that it forms the protoplasm which surrounds it. + +The Contents of Young, Growing and Mature Cell.—A very young cell is completely filled with protoplasm. +As the cell increases in size, the wall grows faster than the protoplasm, so that each cell contains a greater volume of fluid with cell-sap. +In old cells, this substance is called mesophyll, which in a very old cell may be very large. + +The Contents of the Cell.—The cell always contains a substance called mesophyll in addition to the protoplasm and the nucleus. In fact, at one time or another, it contains every element that the plant contains, for the protoplasm in the active mature mesophyll contains starch grains, chloroplasts, chloro- +blasts, leucoplasts, and chromoplasts. Starch and Altenure +grains are also found in cells, while fats and, in some cases, +crystals of calcium oxalate may be present. + +G + +82 +BOTANY FOR BEGINNERS +CHA. +The Cell-Stop is the water fluid which saturates the proto- +plasm and the cell-wall and also occupies the vacuolus. It con- +sists of water which holds in solution a number of organic and +inorganic substances. The substances in solution are either on +their way to be built up into protoplasm, or have themselves +become part of the protoplasm. The substances which are original +substances present in cell-sap are sugar, organic acids, proteins, +and in many cells colouring matter. The inorganic substances +are salt, mineral acids, and mineral bases. Some of these sub- +bodies, in addition to these dissolved substances, may also be pre- +sent in the vacuole, e.g., starch grains, alveolar grains, and +rubber bodies. + +Chloroplasta—in the cells building up the green parts of +plants a green colouring matter is present called chlorophyll. +It consists of a green substance consisting of a number of +granules known by various names, as chlorophyll grains, chloro- +phyll corpuscles, or chloroplasts. A chloroplast is a small mass of protocellature saturated with chlorophyll. In order to +determine whether a substance contains chlorophyll it is treated with alcohol. The chlorophyll is dissolved out, and colourless +grains are left behind; these are called leucoplasta. +It is only when the chloroplasts are exposed to light that chlorophyll is developed. The conditions necessary for the development of chlorophyll are: +(a) a certain temperature, a few degrees below the freezing point; +(b) light; any light will do if it is only intense enough; +(c) a small quantity of iron in the food of the plant. The necessity for iron has been shown by experiments; it is very +interesting, for no iron is found in the chlorophyll itself. The iron is probably necessary in the chemical changes which result +in the formation of chlorophyll. + +From what has been said about light being necessary for +the formation of chlorophyll, it will be understood why it is found +only in the surface cells. The important function of chlorophyll, +which can only be exercised in the presence of light, is shown +by the following experiment: A piece of paper was placed over +it up into carbon and oxygen. The oxygen is returned to the air, but the +carbon combines with the elements of water to form sugar + +VII +THE HISTOLOGY OF THE CELL +8j + +which is eventually converted into starch. The starch grains are formed inside the chloroplasts. + +Chloroplasts ultimately undergo decay, when, as in the case of filling leaves, all that is left of them are a few yellow granules. During autumn the nutritive matters in the cells of the leaves are carried to other parts of the plant to be stored up for future use; and with these nutritive materials the greater part of the chloroplasts are removed. In the Copper Beech the chlorophyll is marked by colouring matter, which is dissolved in the cell sap. + +Leucoplasts.--In those cells not exposed to light, colourless granules are found; these are called leucoplasts. Leucoplasts may be converted into chloroplasts if the cell in which they are present is exposed to light. The change of colour which a Potato may undergo when exposed to light is owing to one of + + +A cross-section of a leaf showing chloroplasts. +B transverse section; a, stroma; a', oil cavity; f', depression; +f, chloroplast. + + +G + +84 +BOTANY FOR BEGINNERS +CHAP. + +the leucoplasts being converted into chloroplasts. The leuco- +plasts perform the important work of converting sugar into starch. The starch granules are seen on the outside of +leucoplasts, not inside as in the chloroplasts. They are of +a denser consistency than chloroplasts, and are flattened in shape. Chromo- +plasts are masses of prota- +plasts which are saturated with colouring matters other than chlorophyll. + +A B C D E +F. fig. 107.—Leucoplasts. A, C, D, E, new cells of tomato. B, old cell of tomato. +E, outer changing colour. (See p. 63.) + +Expt. 79.—Cut a thin section from a Beetroot, and mount it in +water. Examine under a low power. Note— +(1) The protoplasm is yellowish-brown. +(2) The protoplasm lines the cell-wall. +(3) The protoplasm is separated from the sap by a layer of +cellulose. (4) The fresh section is alched for half a minute, before examining it. The coloured sap oozes out because the protoplasm has been killed. + +Expt. 80.—Obtain a few Fern Prothalli from a gutterer. Mount +a small one in water, and examine with a low power. Note— +(1) The prothalli have chloroplasts. +(2) Many of the chloroplasts are undergoing division, as is shown by their shape. Grains shaped like an hour glass are under- +going division. +(3) Place a prothallus in a watch glass and cover with alcohol, and leave it for half an hour. The chloroplasts will be dissolved, +and matter has been dissolved out of the corpuscles, but they still retain their outline. + +84 + +VII THE HISTOLOGY OF THE CELL 85 + +**Extrait. $x_{2}$.—Sow two mustard seeds in two plant pots ; keep the soil moist ; place one on a dark place and the other in a light place. +Observe from day to day. Note :** + +The mustard plants kept in the dark are far longer than those grown in the light, but they are pale yellow or dirty white in colour. + +Those grown in the light are bright green, and are useful for the development of chlorophyll. + +**Extrait. $x_{2}$.—Obtain a few young Potentilla plants (Potentilla anserina) and put them in a weak solution of picric acid for twenty-four hours. Remove them from the solution with a weak solution of alcohol, and examine under a high power of magnification. + +Fig. 109.—Cath from perthallus of Ficus. ($x_{3}$) + +(1) Some of the grains in the protoplasm stain blue. These are starch grains. + +(2) Attached to some of the starch grains small yellowish bodies may be seen. These are leucoplasts. + +Leucoplasts may be seen in colourless tissue in which starch is being stored up. Underground tubers and rhizomes contain them. + +**Starch Grains.** Chloroplasts in those cells which are exposed to light always contain starch grains. In many cases the starch grain is so large that the chloroplast only surrounds it as a thin covering. Chloroplasts are always forming starch at the expense of the sugar which is produced by the constructive activity of the chlorophyll and the protoplasm. +In the green parts of plants starch grains are very small because + +A B C D E F G H I J K L M N O P Q R S T U V W X Y Z + +**Fig. 108.—Starch grains of Wheat.** +A, Starch grain ; small grain. +($x_{3}$-400) ($S$) + +**Fig. 117.—Starch grains of Oats.** +A, Starch grain ; large grain. +($x_{3}$-600) ($S$) + +**Fig. 118.—Starch grains of Indigofera.** +A, Starch grain ; large grain. +($x_{3}$-500) ($S$) + +86 +BOTANY FOR BEGINNERS +CHAP. + +they are always undergoing a change due to the action of a ferment found in the cells. This ferment, which is called diastase, rearranges the starch into sugar. Large starch grains are only found in those parts of plants where they are stored up for food, such as the roots, tubers, and seeds, and differ in shape and size from the grains produced by other plants. By making use of this fact, adulterations of foods can be detected with great facility. + +Starch grains are always striped. The organic centre of the grain around which it grows by the deposition of new material is termed the hilum. The hilum is pro- +duced by the endosperm, and the successive layers which are deposited are also due to the same cause. The outermost layer grows +the same way that a cell-wall grows in thickness, that is, by apposition or by increase in number. In this way compound +grains may be found in cells. These can be divided into two kinds, (a) those called +phloem-grains which are produced by two or more grains coming together under pressure as a result of pressure, (b) true compound +grains which are produced by the same two grains coming together but without any +always a number of layers which bind the +grains together. + +The starch granules can always be detected in +cells by treating them with iodine solution, when they give a deep-blue colour. They thus differ from cellulose which only gives a yellowish colour. + +Starch is a carbohydrate having the same composition as cellulose but differing in its physical properties. When treated with petroleum ether it becomes soluble in water will form a paste. If heated while dry, starch is converted into dextrine and becomes soluble. + +Aleurone Grains. Aleurone grains, or as they are some- +times called, aleurone grains are found in many seeds. Each aleurone grain is built up into a crystalloid and a globoid. +The crystalloid is composed of albumen or proteins, and a + +vn THE HISTOLOGY OF THE CELL 87 + +globoid is formed of a double phosphate of lime and magnesia. If a section of a Castor oil seed be made and examined by the high power of the microscope, the almost globular drops will be seen to be embedded in the protoplasm which is also rich in oil. The proteids are stored up in this phase principally in the form of alcohone granules, large in oily seeds but small in starchy seeds. + +The crystalloids are sometimes found in the cells. These crystals differ from mineral crystals because they are formed by various reagents. + +**Fat.** Drops of oil are found in the protoplasm in the cells of many plants. These drops are very numerous in the cells of the seeds of the Castor Oil plant, Ricinus communis, the fruit of the Olive. The non-nutritive substances stored up as a reserve material in the above plants occur as drops of oil. When the seeds germinate the fat is converted into sugar. + +**Raphides.** In most plants crystals of calcium oxalate are + +A section of a Castor oil seed. A, cell from the endosperm of the Castor grain; B, cell from grain; g, globoid; z, crystalloid. (See p. 63.) +A section of a grain of Wheat. P, protoplasma; z, starch grains; z', cell nucleus. + +88 +BOTANY FOR BEGINNERS +CHAP. + +found. They are always found in vacuoles, and when needle-shaped are called raphides. In many monocotyledonous plants they produce the plant from seeds. See also +**Sugaras**. --Various kinds of sugars and allied bodies are found in the cell-sap. The principal of these are cane-sugar, grape-sugar and cane-sugar. Grape-sugar is found in the fruit of the Grape, and Cane-sugar is found in the Sugar-cane and Beetroot. + +**Expt. 83.--Scrape a fresh cut surface of a Potato into a small dish, and add a few scrappings in water. Examine first with a low power, then with a high power. Note--(i) The numerous starch grains which appear on the surface of the film and the stratified appearance of each grain. +(ii) Run some solution under the cover-glass, and note how it adheres to the edge of it, and placing a drop of the solution on the surface of the film, observe how it spreads, and the solution takes its place. The inline stains remain. +(iii) Add some iodine solution to the film. +(iv) Add some potassium iodide solution. +(v) Add some starch solution. +(vi) Add some potato solution. +The grains swell. + +Fig. 115.--Cell, with a starch grain (x 600). + +(a) A spurious compound grain. + +**Expt. 84.--Obtain a fresh potato, and examine the poorly emulsified or reserve material by removing the outer covering. Cut a thin slice of this material and mount in olive oil. Examine with th high power. Note--(i) The alginene grains or protocells granules. +(ii) Fine starch grains or starch grains. +(iii) A section from a cotyledon of the Almond, and mount in water. Observe the bright-looking droplets in the water ; they are oil drops. + +**Chloride-iodide (Schulze's solution) consists of a mixture of salts dissolved in water containing a small quantity of potassium iodide mixed in water. It is an mild solution of iodine.** + +Fig. 115.--Cell, with a starch grain (x 600). + +VII +THE HISTOLOGY OF THE CELL + +89 + +Formation of New Cells.—It is necessary that new cells should be produced so as to ensure growth and also to continue the life of the plant. The mode in which new cells are produced will depend upon the kinds of organs in which the division takes place. Cell-formation goes on in two different sets of organs, viz., vegetative and reproductive. + +The vegetative parts of a plant are those portions which are of a green colour, such as roots, stems, branches and leaves. The method of cell-formation in all these organs is by simple division. In the root, for example, the first cell thus formed divides into two parts, the protoplasm then separates into two parts, and a cell-wall is formed round each part. In this way a series of cells is formed, each one being larger as the cell from which they were formed. In this method of cell formation there is only a portion of the cell-wall of the new cell which is new, while the rest remains attached to the parent cell. + +The reproductive parts of a plant are those portions which are concerned in the propagation of the species. They are a tax on the vegetative parts, and it is therefore essential that we find the whole of the material necessary to give off the spring a start in life. In all the higher plants this is done by the production of seeds, which produce new plants, and so keep up the species. Cell-formation in reproductive organs is characterised by a rounding off of the protoplasm : and no portion of the parent cell-wall asks in the formation of new daughter cells. + +Fig. 106.—Branches grown from Potatoes. The left-hand figure shows a curious compound grain ; the middle a true compound grain ; and the right-hand figure illustrates a true seed-grain. + +Fig. 107.—Diagram to illustrate cell-divisions. + +2 + +90 +BOTANY FOR BEGINNERS +CHA. +The parent cell contains a nucleus, which, as before divides into two, and each part again divides, and thus there are four nuclei in the cell. The protoplasm now divides into four masses and each portion arranges itself around a nucleus. Each new cell then grows up to its full size, and the mother wall disappears, liberating the four cells. This method of cell formation is called free-cell formation, and it only takes place in reproductive organs. + +SUMMARY + +The Cell.—All parts of plants are built up of microscopic elements called cells. These cells are the building blocks of the plant. + +The Structure of a Cell.—Each living cell consists of—(1) The cell-wall, built up of cellulose. (2) The protoplasm, which fills the cell-wall. (3) The nucleus, a denser portion of the protoplasm. Changes in the structure of a cell may become—(1) Curialized, (2) Plasmodic, (3) Mesodermal. + +Protoplasm is the liquid portion of the cell. It contains the elements carbon, hydrogen, oxygen, nitrogen and sulphur. Protoplasm possesses a certain amount of fluidity or circularity. + +The Nucleus.—All cells possess a nucleus, and in it a nucleus may be found. It is built up of protoplasm and contains a large quantity of phosphorus. + +The Structure of the Cell.—The cell may contain— + +Cell-cup. +Chloroplasts. +Leucoplasts. +Chromoplasts. + +Chloroplasts are portions of protoplasm containing a green colouring matter called chlorophyll. The conditions necessary for the production of chlorophyll are— + +(1) A certain intensity of light. +(2) A temperature above the freezing point. +(3) A supply of carbon dioxide and water. +The functions of the chloroplasts are— + +(1) To convert carbon dioxide into sugar. +(2) To split up the carbon dioxide into carbon and oxygen. +(3) To form starch from sugar. +Leucoplasts are non-green colouring protoplasm. They form starch in those parts of the plant not exposed to light. +Chromoplasts are portions of protoplasm attuned with other colouring matter than chlorophyll. + +Starch granules are formed (1) by chloroplasts in organs exposed to light. + +THE HISTOLOGY OF THE CELL + +light, (2) by karyocysts in the underground stems, roots, &c. Starch grains grow by apposition and interposition. + +The album forms the organic centre of the grain. Successive layers are added to the album, and the whole is surrounded by a layer of starch. A新生 (starch) can convert starch into sugar. Starch granules are formed by the action of enzymes on starch. + +Composition of starch—it is built up of the same elements as cellulose, but with different proportions. + +Alumina Grains—The proteins found in plants are stored up as aluminous crystals. Each aluminous grain consists of a crystallised and a globular. + +Formation of New Cells—New cells are produced by (1) simple division of existing cells, and (2) more complex division takes place in vegetative organs, the latter in reproductive organs. + +Questions on Chapter VII + +(1) Describe the structure of a young cell, and explain how it differs from a full-grown cell. +(2) What is the cell wall formed, and how does it grow in thickness? +(3) To what are the stamens due which can be found in cells? +(4) Give an example of a plant cell that has no chloroplasts. +(5) Describe the structure of a living parenchymatous plant cell. +What do you know about the properties of protoplasm? +(6) Of what is the protoplasm composed? How is it distinguished by the aid of the microscope—a cytoplasm from a (a) liquidified wall, (b) a corky wall, (c) a muscular wall? +(7) What is protoplasm? What do you know about the properties of protoplasm? +(8) What is meant by the circulation of protoplasm? +(9) What are the functions of protoplasm? What important sub- +stances are found in cells? +(10) What is the function of chloroplasts? Where are chloroplasts found? What work can they perform which makes them useful to the plant? +(11) What is meant by the formation of new cells? What is the theory for the development of chlorophyll? +(12) Chlorophyll is green. How? How may a leaf become converted into a chlorophyll? Why are karyocysts and to starch bodies formed? How is it formed, and what are its uses? +(13) To what substance do the green parts of plants owe their colour? Starch is not green. How then do we account for this fact? Can starch alone alone be formed. +(14) What is aluminous grain? Where are aluminous grains found? +(15) How are new cells formed? What kinds of cell-formations are there? + +(17) Explain clearly how starch is formed in a Potato, and from what source it is derived. (1895.) + +CHAPTER VIII +THE HISTOLOGY OF THE TISSUES + +Kinds of Cells. —All cells can be classified according to their shape into (a) Parenchyma, and (b) Proenchyma. + +A parenchyma cell is one in which the diameter of the cell is about the same in every direction. Cells of this description are found in all parts of plants. The ground tissue of a plant is composed of parenchyma cells. These cells are used as a food storehouse for reserve material, as in the turnip. When such cells are very numerous in an organ they are said to form parenchymatous tissue. + +Proenchyma cell is long and narrow. Cells of this description may lose water by evaporation and air water. If a number of proenchyma cells are placed end-to-end, so that the walls are at right angles to the long side walls, the transverse walls may become perforated, and so form a vessel. The vessels thus formed come absorbed after the transverse walls are broken down, and eventually the fully formed vessels contain only air or water. The markings on the walls of the vessels supply the botanist with their characteristic names. + +Fig. 125.—Parenchyma cell from Fruit of Bean. (C'pno.) +Fac. 126.—Da + +130 + +CH. VIII THE HISTOLOGY OF THE TISSUES + +If the walls are pitted (p. 75) they are called *pitted-vessels*. When the thickening of the vessels appear to form a spiral, the vessels are spoken of as *spiral* (Fig. 120). When the markings give them a netted appearance, such vessels are termed *reticulate* (Fig. 120). If the walls are perforated by a single round opening while the rest of the walls remain intact, these vessels are called *annular*. Vessels of the above kinds are found in the wood of all plants. + +**Sieve Tubes.**—In the formation of the sieve tubes or sieve tubes by transverse division of the broken cells they are perforated by fine canals through which the protoplasts pass—for such vessels keep their living contents. + +The canal which keeps the protoplast is called a *sieve plate*. In some plants the longitudinal walls are simi- +![image](image-url) +larly perforated so that sieve plates are also formed in the long walls of sieve tubes are always uninflated, and the ves- +![image](image-url) +sicles contain cell sap. +In close contact with the sieve tubes, and +formed, and these are called *companion-cells*. The +the sieve plates are broken up and disappear, but the com- +long narrow cells are +panion-cells keep both their protoplast and nuclei. + +**Kinds of Tissues.**—When a number of cells are intimately +connected and perform the same kinds of work, they are +called + +93 + +A diagram showing different types of vessel structures. +A. Sieve tube. +B. Longitudinal section, showing sieve plates. +C. Transverse section, showing sieve plates. +D. Longitudinal section, showing annular vessels. +E. Transverse section, showing annular vessels. +F. Longitudinal section, showing annular vessels. +G. Transverse section, showing annular vessels. +H. Longitudinal section, showing annular vessels. +I. Transverse section, showing annular vessels. +J. Longitudinal section, showing annular vessels. +K. Transverse section, showing annular vessels. +L. Longitudinal section, showing annular vessels. +M. Transverse section, showing annular vessels. +N. Longitudinal section, showing annular vessels. +O. Transverse section, showing annular vessels. +P. Longitudinal section, showing annular vessels. +Q. Transverse section, showing annular vessels. +R. Longitudinal section, showing annular vessels. +S. Transverse section, showing annular vessels. +T. Longitudinal section, showing annular vessels. +U. Transverse section, showing annular vessels. +V. Longitudinal section, showing annular vessels. +W. Transverse section, showing annular vessels. +X. Longitudinal section, showing annular vessels. +Y. Transverse section, showing annular vessels. +Z. Longitudinal section, showing annular vessels. +AA. Transverse section, showing annular vessels. +BB. Longitudinal section, showing annular vessels. +CC. Transverse section, showing annular vessels. +DD. Longitudinal section, showing annular vessels. +EE. Transverse section, showing annular vessels. +FF. Longitudinal section, showing annular vessels. +GG. Transverse section, showing annular vessels. +HH. Longitudinal section, showing annular vessels. +II. Transverse section, showing annular vessels. +JJ. Longitudinal section, showing annular vessels. +KK. Transverse section, showing annular vessels. +LL. Longitudinal section, showing annular vessels. +MM. Transverse section, showing annular vessels. +NN. Longitudinal section, showing annular vessels. +OO. Transverse section, showing annular vessels. +PP. Longitudinal section, showing annular vessels. +QQ. Transverse section, showing annular vessels. +RR. Longitudinal section, showing annular vessels. +SS. Transverse section, showing annular vessels. +TT. Longitudinal section, showing annular vessels. +UU. Transverse section, showing annular vessels. +VV. Longitudinal section, showing annular vessels. +WW. Transverse section, showing annular vessels. +XX. Longitudinal section, showing annular vessels. +YY. Transverse section, showing annular vessels. +ZZ. Longitudinal section, showing annular vessels. + +14 + +94 +BOTANY FOR BEGINNERS +CHAP. + +spoken of as forming a tissue. In the higher plants there are three kinds of tissue: vascular tissue, the cells called epidermal tissue, vascular tissue, and ground tissue. The above tissues may be primary or secondary. Primary tissues are formed from the growing cells of the embryo, and the secondary tissues are formed by layers of growing cells which are formed from the embryonic cells. + +EPIDERMAL TISSUE + +Epidermal Tissue.--Those cells which cover the plant and protect the deeper parts from injury, form the epidermis. + +As a rule the epidermis is only one cell in thickness, and the cells do not contain any chlorophyll. The protoplasm of the epidermal cells is reduced to a very thin layer which lines the cell-walls, and the cavities of the cells contain a colourless cell-tap. This is filled with a jelly-like substance, which protects the deeper tissue from a too rapid loss of water. + +Stomata are found in the epidermis of all those parts of plants which are exposed to the air. They are minute openings between which contain chlorophyll and are called guard-cells. The stoma is formed by a young epidermal cell becoming divided by a septum into two equal cells. + +Fig. 125.--Surface view of the epidermis of a leaf of Buhau, showing stomata. +(S. 360.) (S.) + +Fig. 126.--Surface view of the epidermis of a leaf. (S. 360.) (S.) + +VIII THE HISTOLOGY OF THE TISSUES 95 + +The septum then splits open, the opening constitutes the stoma, and the cells form the guard-cells. The size of the stoma depends upon the movement of the guard-cells. The stomata are found on all the green parts of plants, but they are most abundant on the leaves. If both sides of a leaf are alike, the stomata will be equally distributed over upper and lower surfaces. In those plants with floating leaves the stomata are usually found only on one side. + +Stomata can open and shut by the change in the shape of the plant and the external atmosphere—from which interchange the plant obtains energy and food material—goes through through the stomata, which also get water out of a liquid state. Such openings are called **pores**. + +The **stomata** pores are larger than the stomata and are sheathed by hairs. + +Hairs. — From the epidermis hairs are formed for protection (6) for the nutrition of the plant. A single hair consists of a single cell it is said to be unicellular if a number of cells enter into the composition of a hair it is termed a **multicellular** hair. + +Fig. 125. — Waterwort, with a portion of epidermis from a leaf. (S. 83) +Fig. 126. — Epidermis from a leaf of a plant with a large number of stomata. +Fig. 127. — Epidermis from a leaf of a plant with few stomata. +Fig. 128. — Epidermis from a leaf of a plant with no stomata. + +The latter + +BOTANY FOR BEGINNERS +CHAP. + +are found on the stem, leaves, and flowers of most plants. The unicellular root-hair is produced by the outgrowth of an epidermal cell. + +On the surface of the stinging nettle a very large number of hairs are produced. If one examines a section of a single cell at the apex ; the base of this cell is fixed in a number of cells which be- come known as the haustoria. The tip of the hair of a stinging nettle is strengthened with silica, while the rest of the hair con- tains carbohydrates of lime. In the ter- minus, however, they are reduced to starch. When an animal touches the plant the stiff pointed hairs enter its skin and the poison contained in them is injected into it. The well known smarting sensation which a person feels when "netted" is due to the action of these hairs. A slow method of rubbing the wound is to neutralise the acid with the bicarbonate present in the Dock leaf to neutralise the acid with the bicarbonate present in the Dock leaf. + +Emergences. — Emergences are modified portions of the epidermis which grow up through the ground. It is an organ which secretes some sub- stance from the materials which are brought up from below. The net- ticles of the Sundew are well known examples. These secrete a substance very similar to that secreted by the higher animals, and this secretion en- ables the plant to digest any insects which it may catch. (i) The shape of the cells. They are polygonal cells. +(ii) The contents of protoplasm and starch grains. + +Fig. 126.--Stinging hair of Nettle (x 60 x 60). +(i) The shape of the cells. They are polygonal cells. +(ii) The contents of protoplasm and starch grains. These consist principally of grains. + +Cat-scent from a Turpil or from a Potato; mount the thimble in water. + +96 + +THE HISTOLOGY OF THE TISSUES + +vii + +Excr. 83.—Obtain either the stem of the Pumpkin or of the Cucumber; immerse in alcohol. Cut either radial or tangential longitudinal sections. Stain in solution, and examine under the high power. + +(i) The sieve tubes, the transverse walls of which are perforated by minute pores, through which surrounds them being stained dark brown. Note—The substance which surrounds the sieve tubes is a mass of collenchyma composed of collenchyma. The amount of collus present will depend upon the age of the sieve tube (see Excr. 85). + +(ii) The protoplast which lines the tubes and is surrounded by the sieve plates. + +(iii) The shape of the tubes. + +(iv) The companion cells. These are long and narrow, and can be clearly seen under the high power. + +Excr. 85.—From the lower side of the leaf of the Pumpkin, cut a section at any stage of the epidermis; this can be done by raising the epidermis with a needle, and cutting at it; or as a rule, edge of the piece of epidermis is raised with a needle. Mount in water, and examine it with the high power. +Note— + +(1) The continuous outline of the cell-wall. +(2) The stipule-shaped hairs which lie close to the epidermis. +(3) The stomata, which are very numerous. Each stoma consists of a pair of passage-cells—the guard-cells. + +Excr. 90.—Strip from underneath the leaf of the Pumpkin, a piece about one inch square; this coleoptile plant will do as well; a small portion may be examined under the low power, and then examine first under a low power, then with the high power. +Note— + +(1) The stomata, which are very large and numerous. +(2) The upper surface of the leaf is a place of epidermal cells and tracheae in the same way. +(3) The lower appearance with the lower epidermis and note in what ways they differ from those on the upper surface. + +Excr. 91.—Mount in water the root of a germinating Mustard Seed ; examine under the low power. +Note— + +(1) The root-hairs; these are unicellular, and are formed by the out-growth of the cells of the epidermis. + +H + +Fig. 197.—Tissuative tissue. +H + +98 +BOTANY FOK BEGINNERS +CHAf. + +(ii) To some of the root hairs particles of soil adhere. +This adhesion of the root-hairs to particles of soil is due to the con- +version of the outer layer of the cell-wall into mucilage. +Note—Examine a section of a root, and note that a leaf of the +Sunflower; mount in water, and examine under a low power. Note— +The multicellular hairs which are scattered over the surface of the +leaf. + +VASCULAR TISSUE. + +**Vascular tissue.**—If a skeleton leaf be examined it will be +found to consist of a number of hard fibres; these are the **vas- +cular bundles**, or **vascular strands**. These are parts of the +plant, that is, they conduct water from the roots up the stem, +to the leaves, and the elaborated sap from the leaves to +those parts of the plant which require nourishment. The +principal supporting tissue of the plant and form the frame- +work upon which the softer parts are fixed. The bundles always +resist decay longer than the other parts of the plant, and +skilled botanists can often find them in plants which are higher +plants there are two principal types of vascular bundles, they are +known as open and closed bundles. Open bundles are found in +Dicotyledonous plants and closed bundles in Monocotyledonous +plants. + +**Structure of Bundles.**—If a vascular bundle of the +Dicotyledonous type be examined under the microscope, there +will be seen—(a) The **Xylem**, which is nearest the centre of the plant. +(b) The **Phloem**, which is at some distance from the portion of the bundle +most removed from the centre of the plant. +(c) The **Cambium**, which lies between the xylem and phloem. + +**Xylem.**—The xylem is the woody portion of the bundle, and in +the vascular bundle of the stem it is always found nearest to +the pith. It consists of a number of vessels and parenchyma cells. The vessels (p. 93), are long, thin tubes (p. 93), called **vessels** (p. 93), annular (p. 93), reticulate (p. 93), and pitted (p. 93). +The spiral vessels are nearest to the pith, then come the annular vessels, then those with pits, and finally those with reticulations. +In each vessel there is a central canal, surrounded by a wall, +called *protexylem*. The reticulate vessels come next, and the pitted vessels are to be found close up to the cambium. +Scattered about among the vessels, there cells are to be found. These those cells are long and narrow, and in + +VIII THE HISTOLOGY OF THE TISSUES 99 + +some cases have sharply-pointed ends. Proenchyma cells are also found mixed up with the vessels (p. 93). + +In addition to the vessels and the fibrous cells a number of parenchyma cells occur mixed with the vessels; these paren-chyma cells are known as the **phloem**. + +Phloem.—The phloem consists of two portions which are known as the **soft** and **hard**-bast. + +The soft bast is formed by a series of thin-walled parenchyma cells, and parenchyma cells. The sieve tubes (p. 93) are long vessels which have their transverse walls perforated. Companion cells—which can always be recognised in a longitudinal section—are usually found with each sieve tube, and each possessing a large nucleus—found with the sieve-tubes. In transverse sections companion cells are seen between the sieve-tubes, and parenchyma cells as the sieve-tubes. Mixed up with the sieve-tubes and com-panion cells a few parenchyma cells may be found; these are known as the **phloem**. + +The hard bast is composed principally of bast fibres, which are long narrow spindle-shaped fibres, much like the fibres of wood. Proenchyma cells are to be found mixed with the bast fibres. + +Cambium.—The cambium is found between the xylem and phloem, and it is a layer of living cells which differ in the characters of either xylem or phloem. These cambium cells nearest to the phloem pass gradually into it, while those nearest to the xylem pass gradually into it. The cambium cells near the middle of the cambium are thin walled, and contain protoplasm. They are in a state of constant division, and thus form new cells which become xylem on one side and phloem on the other. A tissue composed of cells which can divide in this way is called **meristematic**, because it is capable of dividing up and producing new cells. + +Open and Closed Vascular Bundles.—Those vascular bundles which possess a cambium are said to be open because they can produce new cells at any point along them; but phloem only, without a cambium, they are termed closed bundles because growth in thickness of the bundle cannot go on. Wherever there are phloem are in contact on one side only, they are said to be collateral. + +H 2 + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
100
BOTANY FOR BEGINNERS
CHAP.
The general arrangement of the elements in an open vascular bundle is shown below in tabular form.
Next Pith.
Spiral vessels.Protoplasts.
Anular vessels.Protocollum.Xylem.
Reticulate vessels.End vessels.
Cambium cells.
Sieve-tubes.Soft bast.Cambium.
Companion cells.Open Vascular Bundle.
Blast fibres.Hard bast.Pleome.
Randii Sheath (Pericyle).
+ +The Monocotyledonous Type of Vascular Bundle.---If a vascular bundle of a monocotyledonous plant be examined, two will be found to consist of two kinds of tissue present. They are ---

The first, the Xylem, which always points towards the centre of the stem.

The second, the Phloem, which is turned towards the exterior of the epidermis. + +The structure of such a vascular bundle is much the same as in the dicotyledonous type, only the variety of vessels is not so great. The bundle is surrounded by a superficial sheath of thick walled cells. + +The Course of Vascular Bundles.---If a vascular bundle passes through the stem, it may be seen that it does not run as a single common bundle, because it is common to both the cortex and leaf. The portion of the bundle in the leaf is termed a *leaf-bundle* or *leaf-tract*. It arises from the stem, and it is then spoken of as a *cambial bundle*. + +The arrangement of the bundles in the stem depends upon the phloemaxis (p. 56). If the arrangement of the leaves be in one plane, they will pass through five internodes before it joins on to the bundle below, as in the Walfishwood. + +If the leaves be discursive there will be four rows of leaves on the stem, and the bundle from any leaf will have to pass through two internodes only before it joins on to the bundle of the leaf below. Thus, the bundle which proceeds from a leaf will pass inward for a short distance, then bend and pass down + +VIII THE HISTOLOGY OF THE TISSUES + +The stem until it joins on to the bundle below. The above are the arrangements in most dicotyledonous plants. +The course of the bundles in monocotyledonous plants is very irregular. The bundles from any leaf base pass into the stem towards the opposite side, and run down the stem, when they join on to the bundles below. + +Exr. 53.—Obtain a piece of the stem of the Wallflower with a thick leaf, and examine it under the microscope. To do this insert it horizontally so as to pass through the middle of a leaf; clear away the pith with a fine needle. (1) Observe that the bundles enter the stem from the midrib of the leaf runs inward for a short distance, then turn straight downwards, and strike across at right angles to the stem. (2) Observe that the bundles run through five internodes without joining a bundle below. (3) That there are two smaller bundles that act in the same way. In a long stem there must be four bundles, and therefore there must be five large bundles and ten small bundles cut out. + +Exr. 54.—Trace the course of the vascular bundles in the stem of the plantain. Cut off a piece of stem about one inch long, and cut two leaves on the same side of the stem. Clear the pith away, and notice— + +(1) That the bundle which enters the stem runs inward and then downwards, and strikes across at right angles to the leaf vertically behind it. (2) That each bundle only appears once before it joins on to the bundle below. + +In a long stem there are four main vascular bundles, which correspond to the decussate arrangement of the leaves. + +THE GROUND TISSUE. + +The Ground Tissue.—The tissue which is found in the centre of a stem and between vascular bundles and the epidermis is called ground or fundamental tissue. It usually forms the principal part of the primary tissue of the plant body. + +The Pith within ring of vascular tissue. + +The Cortex between ring of bundles and epidermis. + +The vascular bundles seem to be fixed in the ground tissue, which in a young stem appears around them. It may contain starch granules. + +While the epidermal tissue protects the internal parts of the plant and the vascular bundles perform the office of conduction and support, the ground tissue provides for the nutrition of the plant and forms a store of reserve material. + +103 +BOTANY FOR BEGINNERS +CHAP. VIII + +SUMMARY. +Parenchyma cells are those in which the diameter is about the same in all directions. +Proximal cells are long and narrow. +Vessels are formed by the perforation of the trussanve walls of cells which are placed end to end. The following are very common -- (1) Spongy tissue. (2) Annular vessels. (3) Pitted vessels. +Sieve tubes are formed from cells which have no transverse walls perforated to form sieve plates. + +The vascular system is one system in a plant, viz., the **Epidermal** tissue, which covers and protects the deeper parts of the plant from injury. +Vascular bundles form the supporting and conducting tissue of the plant. +Cortex, which fills in the spaces between the epidermal and vascular tissue. +Stomata are small openings which are found between guard-cells in the epidermis of the aerial parts of plants. +**Keratin** is a hard substance produced by keratinocytes. They may protect the plant from insect pests, or be used for taking food in. +**Keratin** (1) Xylem (2) Cambium (3) Phloem. +If the bundle is closed it will consist of (1) Xylem, and (2) Phloem. +The Coursing of the vascular bundles depends upon the arrangement of the leaves on the stem. + +(1) How does a xylem cell differ from an endothylc cell? +(2) What is a vessel? How are vessels formed? Enumerate the different kinds which are found in wood. +(3) What is meant by function do the vessels of the basal (slave trees) differ from those of the wood? (1862). +(4) What is meant by function do the vessels of the stem of a dicotyledon. Explain how such a bundle differs from that of a monocotyledon. +(5) What is a stem? On what parts of the plant are the stomata clustered? +(6) Give an account of the structure of the epidermis of a leaf. +Why is a vascular bundle? Of what parts does it consist? (1862). +(7) What is meant by function do the vessels of wood and its trunk of a tree, and what is its importance ? (1862). +(8) What is meant by function do the vessels of a root, and explain how it differs from that of a full-grown cell of the same kind. (1862). +(9) What is meant by function do the ground tissue. In what parts of a plant is ground tissue found? +(10) What is meant by function do the longitudinal course of the vascular bundle in a dicotyledonous plant? +(11) What kinds of hairs are found on plants? Of what use to the plant are hairs? + +A diagram showing different types of plant tissues. + +CHAPTER IX + +THE HISTOLOGY OF THE SHOOT AND ROOT + +The Structure of a Dicotyledonous Stem. A transverse section of a young dicotyledonous stem, when examined under the microscope, shows the following +parts (Fig. 28). External +naked epidermis consists of a single layer of cells, many of which may produce hairs ; this is followed by the +epidermis comes out covered with a cuticle on the outside by the endodermis. Inside the endodermis a broken ring of vascular bundles is found, which are separated from each other by a layer of cells known as the pericycle. The centre of the stem is full of hollow cells which form the pith. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +A diagram showing the structure of a dicotyledonous stem. The outermost layer is the epidermis, followed by the cortex, mesophyll, pericycle, phloem, cambium, xylem, and phloem. The centre of the stem is filled with ground tissue. + +Fic. 28. Transverse section of young dicotyledonous stem. In epidermis are naked epidermal cells. In cortex are vascular bundles in the ground tissue. In phloem, phloem cells, cambium, and xylem cells are shown. In ground tissue are ground cells. + +Fic. 29. Transverse section of young dicotyledonous root. In epidermis are naked epidermal cells. In cortex are vascular bundles in the ground tissue. In phloem, phloem cells, cambium, and xylem cells are shown. In ground tissue are ground cells. + +Fic. 30. Transverse section of young dicotyledonous root. In epidermis are naked epidermal cells. In cortex are vascular bundles in the ground tissue. In phloem, phloem cells, cambium, and xylem cells are shown. In ground tissue are ground cells. + +Fic. 31. Transverse section of young dicotyledonous root. In epidermis are naked epidermal cells. In cortex are vascular bundles in the ground tissue. In phloem, phloem cells, cambium, and xylem cells are shown. In ground tissue are ground cells. + +Fic. 32. Transverse section of young dicotyledonous root. In epidermis are naked epidermal cells. In cortex are vascular bundles in the ground tissue. In phloem, phloem cells, cambium, and xylem cells are shown. In ground tissue are ground cells. + +Fic. 33. Transverse section of young dicotyledonous root. In epidermis are naked epidermal cells. In cortex are vascular bundles in the ground tissue. In phloem, phloem cells, cambium, and xylem cells are shown. In ground tissue are ground cells. + +Fic. 34. Transverse section of young dicotyledonous root. In epidermis are naked epidermal cells. In cortex are vascular bundles in the ground tissue. In phloem, phloem cells, cambium, and xylem cells are shown. In ground tissue are ground cells. + +Fic. 35. Transverse section of young dicotyledonous root. In epidermis are naked epidermal cells. In cortex are vascular bundles in the ground tissue. In phloem, phloem cells, cambium, and xylem cells are shown. In ground tissue are ground cells. + +Fic. 36. Transverse section of young dicotyledonous root. In epidermis are naked epidermal cells. In cortex are vascular bundles in the ground tissue. In phloem, phloem cells, cambium, and xylem cells are shown. In ground tissue are ground cells. + +Fic. 37. Transverse section of young dicotyledonous root. In epidermis are naked epidermal cells. In cortex are vascular bundles in the ground tissue. In phloem, phloem cells, cambium, and xylem cells are shown. In ground tissue are ground cells. + +Fic. 38. Transverse section of young dicotyledonous root. In epidermis are naked epidermal cells. In cortex are vascular bundles in the ground tissue. In phloem, phloem cells, cambium, and xylem cells are shown. In ground tissue are ground cells. + +Fic. 39. Transverse section of young dicotyledonous root. In epidermis are naked epidermal cells. In cortex are vascular bundles in the ground tissue. In phloem, phloem cells, cambium, and xylem cells are shown. In ground tissue are ground cells. + +Fic. 40. Transverse section of young dicotyledonous root. In epidermis are naked epidermal cells. In cortex are vascular bundles in the ground tissue. In phloem, phloem cells, cambium, and xylem cells are shown. +104 + +104 +B.JTANY FOR BEGINNERS +CHAP. + +In an old stem of the Sunflower the vascular bundles form a complete ring, and in such an old stem a complete ring of cambium passes through the bundles and across the medullary rays. +Those parts of this cambium ring which lie between the vascular bundles are called intervascular cambium (p. 99). +The interfascicular cambium is formed by cells which are coming meristematic, i.e., they begin to divide up and so complete the ring. This portion of the cambium ring forms + +A diagram showing the structure of a plant stem with various parts labeled. + +Fig. 139.—Transverse section of older stem of Sunflower, showing the first formation of intervascular cambium. The phloem is on the left, xylem on the right, and the intervascular cambium is at the center.
+Fig. 139.—Transverse sec- +tion of part of cylinder of stem of Sunflower. The phloem is on the left, xylem on the right, and the intervascular cambium is at the center.
+NR—root
+XJ—xylem
+ph—phloem
+cb—cambium
+ab—interfascicular cambium + +vascular elements which partly fill up the spaces between the bundles. The whole of the cambium during the active period of growth is meristematic, and so grows out on both sides. Thus, in an old stem the vascular cylinder is formed as follows: + +Expt. 95.—Cut transverse sections of a young stem of the Wallflower and mount in water. Look for a thin section, and note— + +(i) The outermost layer of cells which surrounds the cortex. + +(ii) The cut ends of the vascular bundles. + +(iii) The ground tissue forming the cortex and pith. + +IX THE HISTOLOGY OF THE SHOOT AND ROOT 105 + +Expt. 9a.--Transfer the thinnest section observed in Expt. 83 to alcohol, and let it remain for twenty minutes to bleach it. Now stain it with iodine solution, mount in glycercin, and examine a vascular bundle. + +(i) The endodermis, a single layer of cells containing starch. The starch granules are shown by the arrows. + +(ii) The pericycle, a layer of cells inside the endodermis. + +A diagram of an old stem of Sunflower seen in transverse section, showing an almost complete cylinder of secondary tissue, interrupted by medullary rays. + +Fig. 131.--Diagram of old stem of Sunflower seen in transverse section, showing an almost complete cylinder of secondary tissue, interrupted by medullary rays. + +Co, cortex; ScL, sclerenchyma; Ph, phloem; cb, cambium; cxy, xylem; Pt, pith. + +(iii) The phloem inside the pericycle; the transverse walls of the sieve tubes are stained brown. The sieve tubes are surrounded by parenchyma through which the strands of protoplasm pass may be stained brown. + +(iv) The outer and several layers of cells make the phloem. + +(v) The xylem between the phloem and cortex. This can be easily recognised by the large cavities of the vessels. + +(vi) The cortex contains parenchymatous cells. + +Expt. 9b.--Select a very young stem of the Sunflower. This can be obtained by germinating seeds, and planting out the young plants in plant pots. The stem should not be more than 3in. or less in height. + +A diagram of a young stem of Sunflower seen in transverse section, showing the cortex, phloem, and xylem. + +106 +BOTANY FOR BEGINNERS +CHAP. + +
Outside.Epidermal TissueGround TissueVascular TissueGround Tissue
Epidermis
Cortex
Mesophyll
Pericycle
Phloem
Cambium
Xylem
Phloem
Inside.Epidermal TissueGround TissueVascular TissueGround Tissue
Epidermis
Cortex
Mesophyll
Pericycle
+ + + + + + + + + + + + + +
Cut transverse sections and mount in water. Examine under a low power. Note:
(i) The phloem.(ii) The cortex.(iii) The vascular bundles, which are not united.
(iv) The xylem fibres between the bundles.(v) The cambium, between the phloem and xylem.
+ +Expt. g.—Cut transverse sections from a stem of the Sunflower, which is twice the age of the previous specimen, g., and mount in glycerine. Observe— + +Image of a plant section with labels h, e, f, p, v, b. + +(i) The cambium is seen if a complete ring is formed. + +Expt. h.—Prepare a thin transverse section of a stem of a fully-grown Sunflower, which has been kept in spirit for some time. Mount in glycerine and to harden the tissues. Mount in water and examine under a low power, and note— + +(ii) The phloem, which is formed by the union of the bundles. + +(iii) The cortex, which has lost its chlorophyll. + +(iv) The large multicellular hairs which cover the surface. + +(v) The epidermis. + +Expt. i.—Cut a radial longitudinal section of the stem of the Sunflower, and mount in water. Examine for two hours' power then under a higher power—Note— + + + + + + + + +
(i) The epidermis.(ii) The cortex.(iii) The endodermis.(iv) The pericycle.
+ +Growth in thickness of a Diocotyledonous Stem— +In the young stem of a dicotyledonous plant new additions are made to both the xylem and the phloem by the cambium which is between them. The xylem increases in size by additions to its outer portion, while phloem adds to its inner portion. In this way portions of the cambium become meristematic. Thus, every season new layers are produced, but far more xylem is formed than phloem. The rings which are seen in a cross section of the oak are produced + +ix THE HISTOLOGY OF THE SHOOT AND ROOT 107 + +by the action of the cambium and each ring marks a year's growth. + +Each annual ring consists of a dark coloured layer and a light coloured layer. In spring, when the active period of growth commences, the bark and cortex have been thickened, because during the winter the bark and cortex have been ruptured by the action of frost and changes in temperature. The cambium is at this season three cells wide and vessels which are thin-walled, thus a light coloured layer is formed. During spring the ruptures in the bark are repaired, and as the season advances, more pressure is brought to bear on the cambium. The cambium is thick and thick-walled cells and vessels are produced. These are dark in colour because they con- +tain less air, and thus they darken. A dark-coloured, new lay- +er is formed in the spring. + +The age of a tree can be determined by annual rings, and if the rings are examined and compared the size of the layers will give us some clue to the kind of season when any ring was produced. + +The periderm is found only on those plants which grow in thickness the epidermis is replaced by a new tissue which receives the name of periderm. The periderm is formed by the activity of the cambium. It consists of two rows of cells ; one of these rows forms the phellogen or cork +cambium. The phellogen produces new cells on both its inner and outer surfaces. These cells lose their living contents and form the phelloderm ; those on the outside lose their living contents and their celluose walls are converted into cork. +The cork cells are impervious to water, and so cut off the supply of water to the cortex and epidermis; these con- + +108 BOTANY FOR BEGINNERS CHAP. +sequently dry up and aid in the formation of bark. The parts which form bark and periderm are shown below: + +Fig. 136.--Transverse section of a twig of the White Lily, Lilium candidum and of a tree, L. × spencer. +CHAP. + +Periderm + +Phelloderm +Phellogen +Cork cells + +Bark + +Cork cells +Endodermis +Cortex +Epidermis + +The primary phellogen after a time ceases its activity, and a deeper phellogen is formed. Still later, even this may discontinue its function, until at least two new phellogens which are produced come to be formed in secondary bark. In the bark which is produced by the phellogen, it is called **Scalary bark**; in the bark which is produced by the phellogen, it is called **Scalary bark**; this is found on the Pine and Plane trees. On the other hand, if the secondary bark forms complete rings around the stem, it is called **Hard bark**; in the Honeysuckle, Clematis, and Grapevine. + +Lenticels.--In the Periderm are produced small pores called lenticels, through which air can pass between the plant where the stomata existed in the epidermis. These are openings formed by the phellogen, which produces cells between intercellular spaces are formed (Fig. 135). + +Expt. 101.--Prepare sections of the flower stem of the White Lily, and the leaf of a plant growing in water; if the material has been in solution in glycerin, observe (1) The epidermis, a single layer of cells. + +Fig. 135.--Lenticel from the stem of a plant of the genus *Lilium*.*--Phellogen.* *Ph., phloem.* *X.T., xylem.* (x270.) + +ix THE HISTOLOGY OF THE SHOOT AND ROOT 109 + +(iii) The cortex, which is several layers of cells in thick-bundle. +(iv) The pericycle, which is very strong and forms a thick ring. +(v) The scattered vascular bundles, which are embedded in the ground +tissue. + +Expt. 103.—Cut a transverse section of a two-year-old stem of the +Wallflower. Mount in water, and examine under a low power. +(1) The periderm, which is formed from the pycnenchyma. +(ii) The cork, which is outside the phloem of each cambium. + +The Structure of a Monocotyledonous Stem.—A transverse section of a young stem of the Maize will be made and examined. In the following parts will be seen: +Fig. 136. On the outside an epidermis which consists of a single layer of cells. Im- +mediately inside this, a broad band of thick-walled parenchymatous tissue. This +cortex is a mechanical tissue and is the principal support of the stem. Within this, +parting the stem of part is made up of scattered vascular bundles. +There is no cambium and no growth in thickness can take place as a result of this division. + +Structure of a Dicotyledonous Root.—If a transverse section of a very young top-root of the Wallflower is examined the following structure will be seen: +On the outside the piliiferous layer is formed; this is another name for the young epidermis of the root. Many of the cells of the piliiferous layer are converted into root-hairs, hence the name. +A thin layer of parenchymatous tissue lies just below the epidermis. Inside the epidermis, and limited internally as in the stem by the endodermis, is the cortex. The centre of this cortex is occupied by a large mass of xylem and two masses of phloem. The xylem masses alternate with the phloem masses. In the stem the protostelems + +109 + + +A diagram showing a transverse section of a young stem of Maize. The diagram includes labels for various parts: VB (vascular bundle), G (ground tissue), E (epidermis), C (cortex). + + +Fus. 136.—A portion of a transverse section of a young stem of Maize. VB = vascular bundle; E = epidermis; G = cortex; V.B. = vascular bundle. + + +tio +BOTANY FOR BEGINNERS +CHAP. + +points towards the pith, in the root its points towards the cortex. The vascular cylinder is surrounded by the pericycle. + +**Outside.** +The outer layer with root hairs. +Cortex (parenchyma cells). +Endodermis (cylinder of cells). +Pericycle (single layer of cells). +Fibrous massen (lvs., Wallflower, tws., Xylinum, etc.). + +**Inside.** + +**Growth.** Thickness of the Root.—The roots of dioecyloidous plants in which the stem increases in thickness themselves also grow in thickness. The growth in thickness of roots depends, as it is stems, upon the cambium. The cambium is situated between the cortex and the inside of the phloem. As growth goes on the structure of the root becomes more and more like the stem, until in an old stem the cortex is formed within the phloem, and this is formed in a root from the pericycle; this cuts off the cortex, and the root may be smaller after the second year of growth than at the beginning. + +**The Structure of a Monocotyledonous Root.—In the root of a monocotyledonous plant there is a large central cylinder, surrounded by a number of layers of distinct bundles of wood and bast. In some roots there may be as many as twelve alternating masses of xylem and phloem. The structure is essentially the same, but because the cambium is situated between the cortex and phloem. + +Expt. 103.—Select a young root of the Wallflower, cut a thin transverse section from it, and mount in water. Examine under a low power. + +(i) The pithierous layer with itsoot-hairs. +(ii) The cortex, which is a single layer of cells in thickness. +(iii) The endodermis, which is a single layer of cells surrounding the pith. +(iv) The pericycle, just within the endodermis. + +The wall of each cell is composed of two layers. + +There are only two vascular bundles present. + +Expt. 104.—Obtain a ball of the Hyacinth, and from one of the moistened pieces make a transverse section, mount in water. Examine under a low power. Note— + +(i) The central cylinder is surrounded by the endodermis and the pericycle. +(ii) The very numerous masses of xylem and phloem, which also show its alternating arrangement already seen in the Wallflower. + +IX THE HISTOLOGY OF THE SHOOT AND ROOT 111 + +The Structure of the Leaf.--Each leaf consists of the three tissue systems, but by far the largest portion is ground-tissue. The whole of the leaf is covered by the epidermis, and between the upper and lower epidermis comes the Mesophyll. + +Fig. 137.--Transverse section of young leaf of a plant (Hibiscus). $P$, phloem; $X$, xylem; $C$, cortex; $F$, palisade layer; $L$, lower layer. + +Parenchyma forms a loose tissue full of intercellular spaces. The mesophyll is well supplied with chloroplasts. + +The intercellular spaces of the leaf communicate with the stomata, so that any gas which may enter the stomata finds its way into the mesophyll. The nature of the epidermis of the leaf is always of the nature of cuticle. + +EXPE. 105.--Place a piece of the leaf of the Wallflower between little slabs of carrot, and with a sharp razor cut slices right across. Separate the transverse sections of the leaf so obtained in water. + +Fig. 137.--Transverse section of young leaf of a plant (Hibiscus). P, phloem; X, xylem; C, cortex; F, palisade layer; L, lower layer. + +Fig. 138.--Transverse section of leaf of a plant (Hibiscus). LS, lower side of leaf; LS', lower side of leaf; P, phloem; X, xylem; C, cortex; V, parenchyma; VB, vascular bundle; LS", upper side of leaf. + +112 BOTANY FOR BEGINNERS CHAP. + +glass watch. With a camera's hair brush, mount the thinnest one in water, and examine first with a low power then with the high power. +Notes: +(i) The upper epidermis, a single layer of cells with an outer cuticle. +(ii) The palisade parenchyma, which consists of cells, cylindrical in form, arranged in parallel rows, and containing numerous starch grains in numerous cells in the mesophyll. +(iii) The spongy parenchyma, which consists of loosely-arranged irregular cells with large air spaces between. +(iv) The stomata. Each stoma opens into a large intercellular space—the air chamber. +(v) The guard-cells are separated by a space between two guard-cells. Each guard-cell is sausage-shaped and curved, the ends of the guard-cells being firmly joined together. +(vi) The guard-cells have the cytoplasm and the plasmolysis. +The xylem ends in the palisade cells and the phloem in the spongy parenchyma. +(vii) That the guard-cells contain chloroplasts, and that the other terms are correct. +The Growing Point of the Shoot.—The growing point of the shoot consists of several layers of cells, which are meristematic in character. These cells are protoplasmic, contain many nuclei, and are in a constant state of activity, i.e., growing and dividing until the formation of new meristems stops and all the new tissues of the shoot are developed. There are three distinct layers of cells at the apex, + +A diagram of the growing point of a shoot. PL = Plastid; PR = Periplast; FR = Periblaster; PL = Plasmodesma. + + +10 +(i) Dermatogen.—On the outer portion of the growing point a single layer of cells is formed and divided up by walls being formed at right angles to their surface. This layer gives rise to the epidermis of the young shoot, and is called the dermatogen. +(ii) Periblast.—Below the dermatogen a layer of cells is found, which, at the apical end, forms a single layer of cells thick, but becomes thinner towards its cellular thick. This is the periblast or young cortex, for it forms the cortex. +(iii) Periblaster.—Underneath the periblast is found a group of cells, which gives rise to the whole of the vascular cylinder of + +IX THE HISTOLOGY OF THE SHOOT AND ROOT 113 + +the stem, including the pith, the bundles, and pericycle. This layer receives the name of *pericorm*. + +**Formation of Leaves**—Leaves are formed from the der- +matogen and periblem. The dermatogen grows out and the +periblem forms a sheath around it. A leaf primordium only is +formed, the mesophyll and vascular bundles being formed from +the periblem. + +**Formation of Branches**—When a branch arises in the +axil of a leaf, it is formed from the dermatogen and periblem, +the pleuron taking no part in it. Thus a branch is produced +from the periblem, which is called exogenous, i.e., from the cortex +and epidermis, and it is said to be formed **exogenously**. + +**The Growing Point of the Root**—All the new tissues of +the root are produced from its apex. Though there are no + +Fig. 140.—A transverse section of the stem of *Vicia*, showing origin of aboral cells. +Fig. 141.—Root-cap of *Turfley*. (Magnified.) + +leaves to be developed, there is a root-cap to form. If the young root of a bean plant is held up to the light, two parts can be distinguished, a lighter outer portion and a darker inner portion. +The outer portion is the **root-cap**, and the inner dark one the growing point. The root-cap consists of three layers, as in the shoot. They are +(1.) The pleuron, which forms the vascular cylinder. +(2.) The periblem, which forms the cortex. + +I + +114 +BOTANY FOR BEGINNERS +CHA. +(3.) The calyptogen (which is another name for dermatogen) forms the piliferous layer and the root-cap. Cells are cut off from the outside of the calyptogen to form the root-cap. The root-cap fragments in the soil protects the growing point from injury. It is renewed by the production of new cells, and is replaced by the production of new cells by the calyptogen. + +Formation of Branches—The young roots produce branches either pro- +duced by the pericyle, or outer layer of the vascular cylinder. In some plants, branches arise from the periblem and dermatogen, but in the root they are produced by the pericyle. + +from the Pericyme. +The branches of the root are said to be endogenously formed. When the young root is formed it has to force and eat its way through the cortex and the piliferous layer in order to reach the pericyme. + +A dicotyledonous stem—In a dicotyledonous stem the following parts are present, beginning on the outside: +(1) Epidermis—(or epidermis of periblem); (2) phloem; (3) cambium; (4) phloem; (5) phloem; (6) cambium; (7) xylem; (8) phloem. +Growth in Thickness of a Dicotyledonous Stem—A woody tree grows very slowly at first, but then increases in thickness by means of cambium forming new xylem. Each ring consists of a dark colored wood and light-colored cambium. This process continues year after year until the tree is fully grown. In autumn, the cambium dies and becomes brown. The rings are seen in cross-sections of trees in winter. + +The Root—The root is formed from the pericyle. The pericyle divides up and forms the phloem or cork cambium, which forms on inside a layer of cells that produces new phloem and cork. These layers have lost their living contents. The former is called the phelloderm, and the latter the cork-layer. + +Cortical Layer—This is found in the pericyme. + +A Monocotyledonous stem differs from a dicotyledonous stem in having only one leaf-bundle scattered, and in no growth thickening taking place. + +Boots differ from stems in having alternating masses of phloem and + +IX THE HISTOLOGY OF THE SHOOT AND ROOT 115 + +xylum. Dichotomous root grows in thickness by a cambium which forms new xylem and phloem. A monocotyledonous root only differs from that of a dicotyledon in having more masses of xylem and phloem than the stem. + +Leaves are outgrowths of the stem, and consist of-- + +(1) epidermis, which covers the surface of the vascular bundles; (2) parenchyma, which fills the spaces between the vascular bundles; (3) vascular bundles, which contain the xylem and phloem; (4) sporophytes, which are the leaves; (5) epidermis with stomata. + +The shoot is a plant body which grows in length by the growing point of the stem, viz., (a) The meristem, which forms the epidermis; (b) The epidermis, which covers the vascular bundles and phloem. + +Growing Point of Root.--In roots there are three layers of cells found: (1) The epidermis, which covers the surface; (2) The vascular cylinder, which contains the xylem and phloem; (3) The cortex, which forms the outer layer of the root. + +QUESTIONS ON CHAPTER IX. + +(1) Describe the way in which the stem of a dicotyledonous tree grows. What is meant by primary growth? By secondary growth? + +(2) Describe the structure of the stem of a monocotyledonous plant with the structure of the stem of a dicotyledonous plant. + +(3) Draw a diagram of a section of an ordinary foliage-leaf as seen in transverse section. + +(4) Explain how periderm is formed. How does periderm differ from cork? + +(5) What is a medullary ray? What is meant by primary and secondary growth? + +(6) Describe the structure of the growing point of the stem, and compare it with that of the root. + +(7) What is cambium? What is its position in the stem of dicotyledons? In that of monocotyledons? + +(8) Explain exactly how the root and the stem of a dicotyledonous plant differ from each other in structure, as seen in transverse section under the microscope. + +(9) How does the branching of the stem differ from the branching of the root? + +(10) How can the longitudinal course of the vascular bundles in any stem be determined? + +(11) What is a fascicule? On what parts of a plant are fascicules found? + +(12) Describe the structure of the stem in any monocotyledon, as well as that of a dicotyledon. + +(13) Briefly describe the chief anatomical differences between the structures of stems and roots. + +(14) The stem of an oak tree continues to grow in thickness so long as the tree lives, whereas the stem of a pine tree does not grow any thicker when once formed. Explain the cause of this difference. + +12 + +THE PHYSIOLOGY OF NUTRITION + +**Physiology.**—That division of botany which investigates the work which plants can perform is called **physiology**. Physiology shows how each structure is adapted to the functions of the plant, and what is the use of a plant, can perform. In simple plants like *Prosoecus*—which grows on walls, trunks of trees, and can live if it is only damp,—the entire body of the plant consists of one cell, and this cell contains all the food necessary both for the life of the plant and for the reproduction of its kind. In most multicellular plants, as we have seen, the constituent parts of the plant are arranged in such a way that the structure is connected with the performance of some particular function. + +It is in the higher plants we obtain what is known as division of labour. Each special part of the plant has some special work to perform. The roots collect water and minerals; the leaves take in light, dissolve the soil, stem conducts the water from the roots to the leaves, and the leaves from these materials form sugar, starch, cellulose, and proteins. + +The building material of all living things is carbon. The living bodies, and by which they can be distinguished from non-living bodies, are (i) that from time to time food is taken in and by the plant grown; (ii) movements are carried out by the plant for its own benefit; (iii) reproduction takes place. These parts produce new individuals, i.e., reproduction takes place. + +**Nutrition.**—Those processes which go on in a plant and by which it is able to form new material from the constituents + +A diagram showing the process of photosynthesis. + +30 + +CH. X THE PHYSIOLOGY OF NUTRITION + +of its food are spoken of as nutrition. The nourishment of the plant can only go on where food materials are taken in and so changed that they can become a part of the plant. If the food-supply is not kept up to the death of the plant is a foregone conclusion. Growth can only go on where the food-supply is in excess, and this means that for the production of the energy expended during its present activity. + +The complete food-supply of the plant consists in great part living plant is water. Many succulent plants, such as Tumias and Cabbage, contain more than 90 per cent.of water. Timber which is felled during the driest season of the year seldom contains more than 50 per cent. of water. This timber is dried at a temperature of from 230° F. to 248° F. all water is expelled and solid matter alone remains. + +The greater part of the wood will continue to burn, and the greater part will disappear in the form of gas, a white ash only being left behind. If the gases which are given off during the burning of wood are collected and condensed and examined, they are found to consist of carbon dioxide, water, ammonia, and a compound of sulphur. If these compounds are split up by heat, they yield Carbon, Hydrogen, Oxygen, Nitrogen, and Sulphur. + +Without these five elements no plant can be produced, and they are necessary for the growth of every plant because they can be burnt off. Carbons may form as much as one-half of the dried substance of a plant. The nitrogen seldom exceeds a fourth of the dry weight of a plant. In many cases this amount of Sulphur present is smaller quantities, while the amount of Sulphur present is still smaller. The remaining fraction of a plant's weight is composed of oxygen and hydrogen, and a little mineral matter. + +The ash of the plant is found, when analysed, to contain Phosphorus, Potassium, Calcium, Magnesium and Iron; but there is Silicon, Sodium and Chlorine slight traces of most other chemical elements. Silicon, Sodium, and Chlorine are not necessary for the growth of the plant, but are taken up by it. + +Chlorine seems to be necessary for the nutrition of Buck-wheat, Barley, and Oats, for if these plants are grown in solutions which do not contain this element they do not flourish. + +118 +BOTANY FOR BEGINNERS +CHAP. + +The elements which are found in the ash of a plant are said to form the **incomprehensible** elements of the plant. +The Essential Chemical Elements of Plant Food.— + +The elements which are essential for the life of a green plant are ten in number, but they are as follows: + +Carbon Phosphorus +Hydrogen Potassium +Oxygen Calcium +Nitrogen Magnesium +Sulphur Iron + +Water Culture. The relative importance of the elements given above to the life of plants can be determined by the method of *solution culture*. The plants are grown in distilled water in which certain salts have been dissolved. If the solution contains everything necessary for the growth of the plant, it is said to be a complete solution. In order to determine this in a solution in number of experiments, and observing the effect produced upon the plants, we can draw certain conclusions as to the importance of each element. + +The following can be taken as an example of a solution for water culture: + +Distilled water 1 litre +Potassium nitrate 1 gramm. +Sodium chloride 1 gramm. +Calcium sulphate 1 gramm. +Magnesium sulphate 1 gramm. +Chloride of iron 1 gramm. + +A few drops of a dilute solution of iron chloride should be added. +Seeds of any quickly growing plant, such as Maize, Bean, Peas, or Black-wheat, are germinated in this solution. When the radicles have grown about half an inch long, the seedlings are washed in distilled water. A series of bottles with wide mouths are prepared, and the corks which fit the bottles are suitably split. The seedling is then placed in one bottle, and its roots allowed to hang in the solution. A different solution is placed in each bottle. In one a normal solution is used as a test of the growing power of the seedling. In another a solution is made up from a solution which contains all the essential elements except iron; the plant is of a pale yellow colour, because iron is necessary for the development of chlorophyll. If a mere trace of iron is + +X THE PHYSIOLOGY OF NUTRITION + +119 + +added to the solution the plant changes its colour and becomes green. In fact, if some of the leaves are simply washed with a weak solution of iron they turn green. + +When potassium nitrate is left out of the solution the plant is stunted and dies. + +Expt. 106.--Wagã³ a Turnip and place it in a hot oven for a few days, until it is perfectly dry. Weigh again, and note the change in weight. The water has been driven off, but the substance which makes up the solid matter remains behind. + +Expt. 107.--Twist a piece of stout wire many times round two or three pieces of wood, and branch, and burn them upon a Bunsen or spirit flame upon a plate. Note-- + +(i) The wire is blackened by the combustible matter (the ash). + +(ii) The bark produces the most ash. + +(iii) The wood produces less ash than the grey. + +Expt. 108.--Burn a piece of dry wood in a jar full of air. This can be done by twisting a piece of wire round the wood to hold it with; then blow into the jar a little air. Note-- + +(i) The black ashes fall into the bottom of the jar. + +(ii) It will smell odorous. + +(iii) The jar is empty when the wood is burnt. + +Expt. 109.--The water in the bottle is clear and co- +lourless. (i) The lime- +water becomes +milky when +shaken with +carbonic acid. +(ii) This being the case, +diluted, shows that +burnt air, on car- +bon dioxide is +absorbed by lime- +water. Note. A. Pot plant grown in normal +solution. No. 2. Pot plant grown without getaninum. +No. 3. Pot plant grown with getaninum. +No. 4. Pot plant grown without calcium. +No. 5. Pot plant grown without calcium. +Note. All these plants are healthy and grow well in pure water and fix five of the best developed in all six of the solutions used. + +Fus. 143.--Water Culture.--No. 1. Pot plant grown in normal solution. No. 2. Pot plant grown without getaninum. +No. 3. Pot plant grown with getaninum. +No. 4. Pot plant grown without calcium. +Note. All these plants are healthy and grow well in pure water and fix five of the best developed in all six of the solutions used. + +Extract + +120 +BOTANY FOR BEGINNERS +CHA.P. + +corks. +Mix five solutions for water culture, and number the bottles containing them from one to five. +(1) Let the first be the normal solution given on p. 115. +(2) Let the second contain the potassium nitrate solution. +(3) Mix the third solution without the iron chloride. +(4) For the fourth, omit the potassium nitrate. +(5) In the fifth subduest sodium nitrate for the potassium nitrate, Magnesium sulphate for the iron chloride. +(i) How the plant grows in the first solution: the growth will be slender and yellowish. +(ii) The plant which is grown without the potassium nitrate is stunted in growth. +(1) The plant grown without iron is not green. Wash a leaf with a weak solution of iron chloride; it will turn green. +(2) The plant grown without potassium nitrate is very stunted in its growth. +(3) The plant grown without potassium nitrate, but for which sodium nitrate is substituted, is also abnormal in its growth. This shows that sodium cannot take up the hydrogen of oxygen. +The plants of Fruits can only make use of soluble food, i.e., they can only take in food in solution. The essential elements can only be assimilated when they are united to carbon compounds. +Carbon In the experiments in water culture, the solutions contained no carbon. But if the mature plants at the close of the experiment be submitted to analysis, half their dry weight will be found to consist of carbon dioxide. This comes from Not from the solutions, but from the atmosphere which sur- +rounds the green parts of the plants. The atmosphere may be regarded as a mixture of gas in the following proportion:- + + + + + + + + + + + + + + + + + + + + + + + + + + + +
79.0%20.6%Parts by Volume
NitrogenOxygenCarbondioxide
0.4%0.4%100.0%
+ +The green parts of plants are alone able to take in carbon dioxide and decompose it into carbon and oxygen. That green plants give out oxygen when they are exposed to a bottle of air, or to a bottle of Edeka or Water Cress will do, and exposing them to bright sunlight, when bubbles of gas will be given off. If these bubbles of gas are collected and exam- +ined, they are found to consist of oxygen. If a green plant, or + +X THE PHYSIOLOGY OF NUTRITION + +a portion of a green plant, be placed under a bell jar arranged over mercury, and containing a measured mixture of air and carbon dioxide, and be then exposed to light for a few hours, the volume of the gas under the jar will remain unaltered. +If after the experiment the gas is examined, it will be found to be less carbon dioxide, but more oxygen than at the commencement of the experiment. +This shows that the plant had taken up carbon dioxide and given out some oxygen as the carbon dioxide was used up. +If a leaf which possesses no stomata on the upper surface is placed in a solution of sodium carbonate with wax or vaseline so that no air can enter through the cuticle, and the cover glass which closes off the parts of the leaf beneath is in starch. This seems to point to the conclusion that the carbon dioxide is used up by the plant. + +Recent research shows that— + +1. Under normal conditions, practically the sole pathway for carbon dioxide into or out of the leaf is by the stomata. + +2. When the stomata are closed, and inter- +cellular spaces are blocked, and the pressure of the carbon dioxide is great enough, it may pass through the cuticle. + +3. Although it has been shown that nutritive processes which go on in animals, but in botany it is restricted to the taking in of carbon dioxide by the chloroplasts and sub- +sequent utilization of this substance, other processes of the plants depend upon the assimilation of carbon dioxide. + +Conditions for Assimilation.—Assimilation by green plants can only take place under the following conditions: + +1. A certain intensity of light (either sunlight or electric light will do). +2. A certain temperature, at least a few degrees above the + +Fig. 144.—Stomata and leaves of a plant in contact with water. The leaves have no stomata because of the escape of the oxygen. + +121 + +132 +BOTANY FOR BEGINNERS ¹ CHAP. + +freezing point. Heat is as necessary here as in all other vital processes. + +If a beam of white light is passed through a prism it is bent out of its course and split up into a number of colours. These colours are red, orange, yellow, green, blue, indigo, and violet. The diagram shows that white light is built up of several primary colours. The combinations of these primary colours produce all the other colours. These are just the reverse to those used in chemical processes. The rays of the sun which reach us are composed of all the different kinds of light, but only one sensitive plate of the photographer, or decompose silver salts, are those from the violet end), but they are all mixed together in the atmosphere. The mixture is called white light. Green, blue, and yellow. If a plant is grown under such conditions that only the red, orange, and yellow rays can reach it, and no others, then it will grow very well. But if the amount of starch it will be found against 100 per cent. in white light. On the other hand, if it is grown under conditions where only the red ray can pass through, assimilation falls very low, to from 5 to 7 per cent. only the 100th part of the total amount. + +The changes by which carbon dioxide and water are converted into organic substances are not fully understood at present. We only know the final products, not the stages that lead up to them. + +The first substance produced by plants is sugar. This has a certain activity on the sap. Sugar is most of it fruit sugar. It is most likely cane sugar. If more sugar is produced than can be carried away in the sap, it is converted into starch by the chlorophyll. + +If the green parts of any plants are exposed to light, assimilation commences, and starch appears in the chloroplasts. If assimilation ceases, starch disappears from the chloroplasts and disappears. The disappearance of starch is due to a process called distension, which is found in small quantities in various plants. In this process starch is changed into cellulose or cellulose or another substance, and convert it into a different material. + +Ferments may be living or non-living. The Yeast plant is an example of the former and distension of the latter. + +A very simple experiment was performed to show that assimilation has taken place in a green leaf. From a piece of tindol, cut out the word "assimilation", and encase a leaf with it so that it cannot be seen. Leave the leaf on the tree for a few days, and then bleach the leaf, and treat it with iodine solution. The word assimilation will appear on the leaf. The whole of the leaf, with the + +THE PHYSIOLOGY OF NUTRITION + +exception of where it had been exposed to light, is pale in colour. This shows that light is necessary for the formation of starch. + +**Only Green Plants can Assimilate.** These plants are the sole destitute of chlorophyll must obtain their carbonaceous food in some other form. The Dodder and the Broom-rape obtain their carbon from the host plant (p. 24) upon which they grow, but the majority of green plants obtain the carbon which they require from decomposing vegetable matter; they are called **saprophytes.** The Bird's Nest Fern is one example. + +EXPT. 110.—Place a little water in a saucepan, and leave it on a table for an hour or two. Then pour the water into a bottle, and let it run till the bottle is full. (i) Show that this shows that carbon dioxide exists in the air. (ii) Show that this shows that carbon dioxide exists in the air. + +EXPT. 111.—Prepare some carbon dioxide by acting on marble with hydrochloric acid. Place a few pieces of marble in a test-tube, and add a few drops of hydrochloric acid. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place a few pieces of marble in it. Place a few drops of hydrochloric acid in another test-tube, and place + +124 +BOTANY FOR BEGINNERS +CHAP. + +EXTR. 113.—Place a green plant under a blue filter, and expose to light for a few days. Examination is made by the same method given in Expt. 112. Note: +(i) The leaves do not turn to dark in colour with the iodine solution. +(ii) This is due to the blue glass cutting off all the rays except the red and violet, which are absorbed by the iodine. +Experiments show that the active rays are those from the red end of the spectrum, but as white light contains all these rays in addition to blue and violet, there will be even more of the red than of the other light than under the influence of the red, orange and yellow rays. + +EXTR. 114.—Obtain a strip of tin foil and fix it over a portion of a leaf, so as to prevent it from being exposed to light. Use the plant for two or three days, and then examine it in the way advised in Expt. 112. +(i) The part of the leaf which has been covered with tin foil is of a pale green colour. +(ii) The remainder of the leaf is of a dark blue colour. +EXTR. 115.—Take a plant with variegated leaves, and place it in darkness for a few days. Now place the plant in bright light for two hours, and then again put it in darkness for a few days. +(i) That it is only the green parts of the leaf which colour blue. +(ii) This shows that it is only the green parts of plants which can assimilate. + +Other Elements in the Food of Plants.—Hydrogen. +All plants can obtain hydrogen from water, but not from mineral salts. +A hydrogen atom is necessary for the life of the plant, for it is an element in composition, as we have seen, of cellulose, starch, protoplasm and photosynthesis. +Cyanogen.—Plants can take up oxygen in a free state, in combination with water, and in mineral salts. + +Respiration.—Free oxygen is necessary for the life of every cell. It is also necessary for free oxygen and the giving out of carbon dioxide is spoken of as respiration. Every living cell in a plant requires oxygen for its activity. +In respiration and photosynthesis, these two assimilat- ion are distinct processes. Green plants are alone able to assimilate under the influence of light; they take in carbon dioxide and give out oxygen. +Respiration is carried on by all parts of plants no matter what their colour may be, and at all times, from the commence- ment of germination until the plants die. Oxygen is taken in + +X +THE PHYSIOLOGY OF NUTRITION +125 + +By living plants and carbon dioxide given out both during light and darkness. +During assimilation the plant gains weight, but during active respiration there is a loss of material. The loss is caused by +with the carbon compounds of the air and carbon dioxide. This loss of weight due to the absorption of oxygen supplies the plant with energy, by means of which it becomes able to assimilate. If a plant which is placed in an atmosphere of pure nitrogen, in air from which the oxygen has been absorbed, its active respiration ceases at once. It has been calculated that this active assimilation will counterbalance the loss by respiration. + +The heat produced by Respiration. A thermometer surround- +ed with moist cotton seeds registers a rise of temperature. +Flowers which are actively respire produce both heat and carbon dioxide. This can be shown by placing a number of + +A diagram showing a plant in a glass container with a thermometer attached to it. +A B C D E F G H I J K L M N O P Q R S T U V W X Y Z + +Fig. 146.-Experiment in respiration. B, an inverted glass bulb containing a thermometer; C, a plant in position by cotton wool; B', A', solution of quinine potash; P, paper; Q, cotton wool; R, water; S, soil; T, soil; U, soil; V, soil; W, soil; X, soil; Y, soil; Z, soil. + +126 +BOTANY FOR BEGINNERS CHAP. + +flowers in a flask and holding them in position by a plug of cotton wool pushed into the neck of the flask. Fit the flask in an inverted position on to a cork through which one end of a tube (open at both ends) passes. The other end of the tube dips into the water. The air in the flask is replaced by caustic potash fumes. As the flowers in the flask use up the oxygen and give out carbon dioxide, since the latter can be dissolved in water, the pressure within the flask gradually rises in the tube. This is because of the diminution of the pressure inside the flask. If the gas in the flask be tested, a certain amount of carbon dioxide will be found. This caustic potash solution can be proved to have increased in weight. If the temperature of the flask be noted a rise of temperature will be observed. Fig. 146 shows the apparatus which can be used for this experiment. + +Conditions necessary for Respiration.—The conditions under which respiration may be stated as follows: + +1. Plants must have light. +2. An atmosphere containing free oxygen is necessary. +3. A certain temperature is most favourable. If seeds are kept in a warm place they grow slowly, but if moved to a warm place the respiration increases. + +Parts of Plants which Respire.—Usually— + +1. Every living cell at all times; dead parts of plants cannot respire. +2. Growing young seeds which require great vigour. +3. All parts which are growing actively. There is always a rise of temperature due to the very active respiration at these times. +4. Developing flowers; during the time of flowering there is a great demand for oxygen, and a rise of temperature always takes place. + +Uses of Oxygen.—Plants require oxygen for two purposes. +In the first place it is necessary for the building up of cellulose, starch, sugar, proteins, and protoplasm. It is also necessary for respiration, that is, for breaking down food and gainin' the necessary energy for the vital processes to be carried out. + +Exr. 118.—Keep a few peas in water for twenty-four hours, and place them on damp cotton-wool at the bottom of a bottle. Close the + +THE PHYSIOLOGY OF NUTRITION + +127 + +bottle with a tight-fitting cork, and keep the peas warm for two days. +Note— +(i) That when the cork is removed and a lighter tap put in, the moisture will escape. +(ii) If a little water-lime is shaken in the bottle, it turns milky. +(iii) The peas will then be found to have increased in weight up by the germinating seeds, and that carbon dioxide has been given out. + +Expt. 117.—Place a few peas on damp cotton-wool at the bottom of a test-tube which contains a solution of cane-sugar. Through the cork pass a glass tube bent into the shape of a U, one end of which is in contact with the air in the tube, and in the glass tube pour a little liquid. +(i) The liquid stands at the same level in both arms. +(ii) As the experiment goes on, the liquid rises in the upper arm, which is in direct contact with the air in the tube. +(iii) The rise of the liquid is due to the oxygen in the bottle being used up by the peas, and also to the carbon dioxide which they give out being absorbed by the sugar solution in the bottle. The pressure in the bottle being less than atmospheric, this excess of gas is forced towards the bottle. +(iv) In order to show that the cane-sugar paste can be heated without loss of weight, it may be found to have increased in weight. +Expt. 118.—Obtain two Potato tubers, one dry in a hot oven, and one other in a damp dark room. Examine note— +(i) The one in the oven, because water is driven off, loses weight. +When it is perfectly dry, weigh it, and record the change in weight. +(ii) The one kept in a damp room, and pro- +duce small pale leaves and small tubers. +(iii) The potato tuber was cut open, and reserve material in the +tuber has been used up. +(iv) The tuber was allowed to grow, with the stems, leaves, and tubers which have been produced, and produce them in a hot oven until all the water has been driven off. +(v) With dry residue. It is lighter than the residue obtained from the first tuber dried in the oven. This loss of weight is due to respiration. During the whole of the time of growth, oxygen was taken + +Fig. 143.—Diagram illustrating how much oxygen and carbon dioxide are given out by green plants during photosynthesis. (a) CO2 changes into O2. (b) CO2 changes into H2O. (c) O2 changes into CO2. (d) O2 changes into H2O. The oxygen produced by photosynthesis is used up by respiration. CO2 is released by respiration. CO2 is absorbed by the leaves through stomata. + +128 +BOTANY FOR BEGINNERS +CHAP. + +in and carbon dioxide given out, let us, the plant being in the dark, no +chlorophyll was produced and no assimilation could go on. +(5) This experiment shows that there is a loss of weight due to +respiration by the plant, which, during the day, is used up by the carbon of +the plant to form carbon dioxide. + +EXPT. 119.--Place some germinating Peas in a funnel, as shown in +Fig. 148, so that they remain in contact with a thermometer. Cover the +apparatus over with a cardboard box, and make a hole in the bottom +through a hole in the box. Note-- + +There is a rise of temperature due to the respiration which goes on. + +The Nitrogen of Plants.-- + +In the water culture experiment we found that when the solution was +kept in the solution without com- +pounds of nitrogen was stunted, +and when we added a small +want of nitrogen, though sur- +rounding it on every hand there +was plenty of it, the plants did +not grow. The plants cannot use the free nitro- +gen of the air. Nitrogen must +always be present to a plant +in its food material. + +green plants obtain the nitrogen necessary for their growth from +the nitrates or mineral salts which contain it. These are formed by the action of the soil which may be dissolved by water, which is subsequently absorbed by the roots and is introduced into a plant. +Nitrogen is necessary for their growth from + +Carnivorous Plants able to obtain the greater portion of the nitrogen necessary for their growth from the animals which they are able to eat. + +The Sun-Dew (Fig. 150), which grows on the mornas in Lanca- +shire, England, is a Nota-plant. It is one of the plants of United Kingdom, an example of such a plant. The name Sun-Dew has been given to the plant because, when the sun shines, it appears to be covered with dew. The leaves are covered with hairs called tentacles, on the end of which minute + +Fig. 148--Diagram illustrating the rise of temperature due to respiration. + +X THE PHYSIOLOGY OF NUTRITION 129 + +glands are developed. The glands secrete a fluid which is very much like the gastric juice of the higher animals. It is this + +Dodder plant with tendrils and leaves. +Section of dodder showing how the tendrils enter the host plant. +Section of dodder showing the structure of the leaf. + +Fig. 140. Dodder. -In the middle a plant of the Dodder is shown parasitic on a host plant. On the left, a section through one of the leaves shows how the tendrils enter the host plant. On the right, the flaxworm which eats the dodder is shown. + +fluid which causes the plant to appear to be covered with dew. If a small insect sees the glistening fluid it comes towards + +135 +BOTANY FOR BEGINNERS +CHAP. + +it (doobless with visions of honey), and a leg or a wing comes in contact with the end of a gland and the fluid holds it tight. +The struggling insect smears itself more and more with the deceptive fluid, and, strange to say, all the tentacles on the leaf begin to move towards the gland, and the insect is drawn in. +More and more fluid is poured out until when becomes quiet. The leaf remains closed for a few days, and when it opens a little + +Sundew plant +Fig. 130.—Sundew. + +Butterwort plant +Fig. 131.—Butterwort. + +indigestible matter is blown away. The remainder has been absorbed by the leaf for its nutrition. + +Another English carnivorous plant is the Butterwort (Fig. 131), which grows in damp places. A rosette of leaves grows close to the ground. The leaves are green, yellowish-green, or brownish-green, and have long hairs which secrete a sticky fluid. The wind is always blowing the dead bodies of small animals about, and if one of these dead insects comes into contact with the sticky fluid, it is caught by the leaf, which is always somewhat curved, moves a little and pushes the body before it. The hairs secrete an acid fluid capable of + +136 + +THE PHYSIOLOGY OF NUTRITION + +131 + +decomposing the dead bodies, and thus the plant is able to obtain a portion of the nitrogen which it requires. +In many parts of the ditches, ponds, or pools in Scotland and Ireland an aquatic carnivorous plant is found. Growing from it are two bladders, one of which is about an inch long and from one-eighth to one-quarter of an inch in diameter. It receives the name of the Bladderwort (Fig. 152). + +![Image](image) + +Fig. 152.—Bladderwort. + +Fig. 153.—A, bladder of Bladderwort ; B, section of bladder ; C, wall of bladder, more highly magnified. + +Entrance into the bladder is effected through the opening at one side. The opening is guarded by a valve which is a sort of trap-door opening inwards and sloping towards the cavity. The valve is guarded internally by a number of stiff hairs, and externally by a number of long multicellular hairs. The bladder (Fig. 153) is lined with a number of cells which can absorb materials from the bladders. + +The whole of the apparatus is a trap for small aquatic animals. They can enter but never return. The animal pushes against K + +A, B, C images showing different views of Bladderwort. + +132 +BOTANY FOR BEGINNERS +CHAP. + +the door, which gives way and allows it to enter. It tries again and again to push the door open but it will only open inwardly. +After a time it dies ; decomposition sets in, and the products are absorbed by the cells which line the bladder. +In most parts of the world they are carnivorous plants. +Well-known examples are the Venus' Fly-trap (Fig. 154), which grows in South America, and the pitcher plants, which are very widely dis- +tributed. +Most of these plants grow in soil which is very poor in nitrate, with lowy bog plants for their companions. They feed through their power of entrapping small animals that they catch in their bladders. +It has been proved by experiments that if car- +nivorous plants are grown so that no animal food can be obtained that they are stunted in their growth. +Leguminous Plants +The members of the +Bean family are able to obtain the nitrogen which they require in a different way from most plants. If a Clover or Pea plant is examined, its roots examined, they will be seen to be covered with a number of nodules, or root-tubercles, as they are called. These are produced by bacteria, and contain a large amount of nitrogen. The Bacteria penetrate through the root-hairs into the cortex of the root, and so produce the tubercles. The Bacteria live in and around the tubercles, and take up the nitrogen from the air in the soil, and build up this nitrogen into compounds, which are passed on to the plant. The plant most likely gives carbonaceous compounds to the Bacteria in return for nitrogen. + +Fig. 134—Venus' Fly-trap. + +Bacteria + +X +THE PHYSIOLOGY OF NUTRITION +133 + +The Bacteria form with the Leguminous plant a life partnership, which is called *Symbiosis*. That it is an advantage for the Leguminous plants to have the Bacteria living in the soil is certain, for those plants with the best development are those that have them. + +The relation of the Bacteria with the plants which belong to the Bean family is very interesting. The farmers can now obtain Bacteria to mix with the seeds of the above plants when sowing, and by so doing, which mixed with the seeds receives the name of *nitragin*. If a little soil from a field where good root-tubercles are produced be taken and applied to a soil which will not pro- +duce root-tubercles, such soil will then be improved, and the plant will be- +come strong and healthy: + +EXPT. 120.—Pull up a well-developed +root-tubercle of the clover on the roots. +Note: +(i) The tubercles on the roots, +are shown in Fig. 15. +(ii) The tubercles are connected at a root, +so as to pass through a root tubercle and examine it with a hand-lens. +(iii) The tubercle is a solid portion of a +root having a root-tubercle in its center. +(iv) The tubercle has a high power, and note the structure. +EXPT. 121.—Pull up a stunted Clover +plant (Fig. 16). Note: +(i) The roots have either only very few +tubercles or none at all. +(ii) The general appearance of the +plant. +(iii) Experiments 120 and 122 show that +such poor tubercles exert a favorable influence on the growth of the Clover. + +EXPT. 122.—Prepare two pot plants in the following way—(a) Fill one pot with rich soil from a field in which Clover grows to perfection; +(b) fill the other one with sand which has been moistened to a high + +Fig. 15.—Root-tubercles on the roots of a Leguminous plant, *Medicago* (R.) +133 + +134 +BOTANY FOR BEGINNERS +CHAP. + +temperature by placing in an old tin and applying heat to it. See p. 50. +Chlor-oven seeds in each give to the water only, until to (a) give the solution described on page 128. From time to time pull up a plant from each pot and examine it. + +(i) The difference in the size of the plants. +(ii) The difference in the root-tubercles. + +Remaining Elements in Plants.--Nitrogen.--Plants take nitrogen from the atmosphere. Ammonia, potassium, and calcium are the most useful to the plant. Sulphur enters into the composition of proteins and protoplasm, and is therefore essential to the formation of protoplasm. Phosphorus.--Plants take in phosphorus as phosphates, and as free phosphoric acid. A common phosphate is calcined phosphate, or phosphate of lime. Phosphorus enters into the composition of the nucleus, and appears in those chemical changes upon which the growth of the plant depends. + +Potassium.--There is a very large variety of forms in which potassium can exist in nature. These include sulphates, phosphates, and chlorides. As a rule clay soils possess plenty of potassium, and it is very seldom that a compound of potassium is applied to the soil without its being absorbed by the plant and in the formation of protoplasm. The solid matter of a plant contains as much as 3% per cent. of potassium. + +Calcium.--Calcium is also found in many forms. When its growth is absorbed in the form of sulphates, phosphates, or nitrates. The work which calcium plays in the economy of the plant is not fully understood. Plants cannot live without it; and the effects of its deficiency supply a good reason for its needed growth. + +Magnesium.--Magnesium can be taken by plants from all its compounds except the chloride, which seems to be injurious. +Very little is known as to the use of magnesium, but our experi- +ments in water culture show that it is necessary for the healthy +growth of green plants. + +Iron.--Green plants, as we have seen, require iron in their food for the formation of chlorophyll. This element can be absorbed by plants from water; but it is only an essential element for the nutrition of green plants. + +The Non-Essential Elements of Plant Food.--A very large number of elements which plants take in with their food they can do without. + +X +THE PHYSIOLOGY OF NUTRITION + +Sulphur. This element is taken in by the roots of plants in the form of soluble sulphites. It is very largely deposited in cell-walls, and partly in the form of sulphate of ammonia. Sulphur is also capable of penetrating through external walls which itlicons are present. When all and the cored grains have a very large quantity of sulphur in their ash; but this is not so with the leaves, which contain only a small quantity of Chlorine. Sodium is one of the most widely distributed of all the elements, and is found in every part of the plant. It is present in Chlorine. The ash of all plants contains a little chlorine, but it is not found in any great abundance in the leaves. The chlorides of sodium and potassium are very abundant in the leaves, and it is difficult to grow better if they are supplied with chloride; Maltose will grow in the absence of both sodium and potassium, but in the presence of both, it will grow much better. + +SUMMARY. + +Physiology. The division of botany which deals with what a plant can do is known as physiology. The higher plants show division of labour, i.e., each part of the plant performs a special kind of work, e.g., photosynthesis, respiration, etc. The plant must also change its food, thus enabling the plant to form new tissue, is spoken of as being autotrophic. + +The Essential Elements of Plant Food are— + +1. Carbon. +2. Hydrogen. +3. Oxygen. +4. Nitrogen. +5. Sulphur. +6. Phosphorus. +7. Potassium. +8. Magnesium. +9. Calcium. +10. Iron. +11. Copper. +12. Zinc. +13. Manganese. +14. Boron. +15. Iodine. +16. Selenium. + +When we consider that a plant is grown in a solution the ingredients of which are known, we can find out what the plant requires for its growth and development. + +The Food of Plants.—Plants can only take in their food in the form of compounds containing carbon dioxide and water. + +Carbon dioxide obtained by green plants from the carbon dioxide of the atmosphere. Only the green parts of plants can decompose carbon dioxide into carbohydrates under conditions favourable to respiration. + +Assimilation.—The absorption of carbon dioxide and its conversion into carbohydrates is called assimilation. The process proper for assimilation to take place (a) A certain intensity of light; (b) A certain temperature; (c) A certain amount of oxygen; (d) A certain amount of water. + +Respiration.—The respiratory processes which take place in their cells in the form of carbon compounds other than carbon dioxide. + +The energy necessary for these processes comes from sunlight. + +The Hydrogen necessary for a plant is obtained from water and ammonia salts. + +Photosynthesis required by a plant (a) in a combined form as a food, and (b) in a free state for respiration. + +Plants require oxygen and must have free oxygen for respiration. This oxygen unless with the carbon of the plant and forms carbon dioxide and water, which are exhaled from the plant's body. Assimila- tion is two different processes: the plant gains by the first the energy necessary for assimilation and growth, by the latter it gains weight. + +135 + +136 +BOTANY FOR BEGINNERS +CHAP. X + +Heat is produced by respiration. Plants require (1) In both light and darkness; (2) In an atmosphere containing free oxygen; (3) At certain temperatures; (4) In a cell, (5) Germinating seeds; (6) The growing parts of plants; (7) The flowers. + +Mosses, ferns, and other plants are able to live in the soil because they have the ability to obtain their food from the water in which they grow. The nitrogenous matter of the soil is used by the plant for its growth through the agency of bacteria, which grow in tubercles on their roots. These bacteria are unable to live without the bacteria, i.e., there is a life- +partnership between them. + +QUESTIONS ON CHAPTER X. +(1) What is meant by plant physiology? +(2) Explain how "food is obtained by division of labour"? - +(3) What do you know about: +(a) The amount of water found in plants? +(b) The amount of carbon dioxide in plants? +(c) The ash left after the combustion of a plant? +(d) The amount of water lost by a green plant absorbed as food from the soil? and briefly state what is the special use of such water? +(4) Explain why it is that starch-grains are formed in the chlorophyllb of young leaves? +(5) Explain how it is that a green plant cannot carry out its nutrition in darkness. +(6) What part of its food does a green plant obtain from the air? In what form, and under what conditions, is it taken in? (1880) +(7) Why is it that a green plant can make use of the carbon by green leaves? State the means by which you would prove that a green plant can make use of carbon dioxide. +(8) Give an account of the use of chlorophyll in the nutritive pro- +cesses of plants. +(9) From what source and in what forms do plants usually absorb: +(a) mineral salts? +(b) carbon dioxide? +(c) water? +(d) organic food? +(e) oxygen? +(f) heat energy? +(g) light energy? +(10) Plants both absorb and give out carbon dioxide. How much per- +cently does each take up and give off? (1884) +(11) What is meant when it is said that the nutrition of plants differs from that of animals? (1896) +(12) Is starch a starch? Explain how it is that, if a green plant be +kept for a day or two in darkness, no starch is to be found in its leaves. +(1897) +(13) How may the necessary chemical elements for the nutrition of +a green plant be obtained? +(14) What is the importance of carbon to a plant? From what +source does a green plant get its carbon, and how is it assimilated? (1899) + +A diagram showing the process of photosynthesis. + +CHAPTER XI + +THE ABSORPTION AND MOVEMENT OF WATER IN THE PLANT + +Absorption of Water and Minerals.--It is a well-known fact that if plants are not supplied with water they cease to grow. The water which is absorbed by the plant is a substance which a plant requires for its growth are taken from the soil with the exception of nitrogenous substances which are obtained from the air. That the roots are the organs which take in water is shown by the experiments in water culture. The parts of the roots active in absorbing water are the root-hairs, and the uncuticularised portions of the younger roots. Root-hairs are unicellular and thin-walled, and consist of a single cell. These root-hairs pass between the particles of the soil, and by their intimate connection there is formed a capillary tube through which solution. Even in a dry soil there is a certain amount of water round the particles, held there by the attraction of the particles of water from particle to particle by the same capillary force. Capillary attraction similarly causes water to rise up a glass tube. If one corner is wetted it also determines the flow of out of the wick of a lamp. + +EXPERIMENT.--Obtain two slips or pieces of window glass and a tumbler partly filled with a coloured liquid. Place the pieces of glass so that + +A diagram showing a cross-section of a root hair, with a small droplet of water at its tip. +Fig. 133.--Tip of root-hair, with droplet of water at tip. (See p. 15.) + +138 +BOTANY FOR BEGINNERS +CHAP. + +there is a little space between them, and dip them into the liquid in the tumbler. Note:— + +(i) The coloured liquid rises between the slips of glass. +(ii) The greater the distance between the slips of glass, the greater is the width of the opening between the slips. The greater the distance between the slips of glass, the more closely they are together. The nearer they are together the higher the coloured water will rise. + +To show how the particles are held in suspension. + +The finer the particles in the soil the more water will be held by it. The interstices between the particles of the soil form so many capillary tubes, up which the water rises, and by which it is held. + +Absorption—The root-hairs make their way into the interstices, and come into close contact with the water round the particles of soil. They become wetted, and their outer cell-wall of the root-hair, or unicellularisation portion of the root ; it thus reaches the interior of the root-hair and eventually passes up into the cells of the root. This is shown by placing a plant cell into the soil. That plants do take in water by their roots can be shown by growing a plant in water in which a little carmine has been dissolved. The roots will be found to have taken up some of the carmine, but only those parts of the roots being stained internally for a considerable distance above the water. Only those substances in the soil which are soluble may be taken in by the plant. This can be shown by the following experiment. + +Expt. 125.—Put a little powdered cork in water, and place the roots of a growing plant in this solution for several hours, and examine in the following way: + +(a) Examine under the root ; it will be coloured externally for a short distance above where the water stands. + +(b) Examine under both root and mount in glycerine. + +Examine under the low power of the microscope : the section is seen to be stained. + +(c) This shows that the soluble cane can pass along with the water through a living plant. + +Expt. 126.—Place a little powdered carmine in water, and place the roots of an actively growing plant so that they dip into the mixture. Note: + +(i) The carmine does not dissolve, but remains suspended in the water. +(ii) The carmine does not pass through living plant tissue. +Examine with low power of the microscope. Observe the carmine has not passed through living plant tissue. +(iii) It is only the soluble constituents which can pass through the cell-wall along with the water. + +**XI. ABSORPTION AND MOVEMENT OF WATER** + +**Osmosis.—Since nutrient substances must pass through the closed walls of cells in order to reach their interior, it follows that they must be in a soluble condition.** + +How is the interchange between the fluid in the plant and that in the soil effected? The cell-say in the plant is separated from the water in the soil by the permeable cell-walls. + +The absorption of the solution from the soil is nothing more than osmosis. The passage of water through a membrane is called osmosis, and for this to take place it is necessary for the fluids to be of different specific gravities. In the case of water, however, this exterior of the plant to the interior called the **endo-** +current, and one from the interior of the plant to the exterior, called excurrent, is impermeable. This is due to the fact that water is much richer in substances which set up osmotic currents than the water in the soil, or in other words is heavier bulk for bulk; a concentration of solutes takes place on both sides of the cell-wall while very little of the cell-say passes into the soil. The giving out of the acid-cell-say by the plant in exchange for the solution of salt in the soil is known as **exsorption.** The soil itself contains a variety of materials insoluble in pure water but which are dissolved in a weak acid. If a plant is grown over a slab of polished marble so that the roots come in contact with it, the acid will dissolve some of these materials and leave their impression on the slab of marble. These impressions are produced by the acid-cell-say dissolving some of the material. + +Expt. 126. (i) Dip a piece of alum limbus paper in a weak solution of sulphate of lead. Note— + +(ii) Dip a piece of red limbus paper in a little caustic soda solution ; it changes its color. + +(iii) These tests are used to see if a substance is acid or alkaline. + +Expt. 127.—Pull up a green plant 1/2 its roots and place a piece of black rubber over them and let them grow. Note— + +(iv) The paper gradually becomes red. + +(v) The plant dies. + +Expt. 128.—Obtain a piece of limestone and marble and polish it by rubbing one side on a piece of flagstone. Place the polished limestone in a pot with water and keep it at room temperature until all the limonates have disappeared. Keep the plant moist and place the pot where there is + +xii + +140 +BOTANY FOR BEGINNERS +CHAP. + +plenty of light. At the end of some twelve weeks pull up the plant, +take the piece of limosine root, and wash it. Note— +(i) The markings on the limosine show where the roots touch each other. +(ii) These markings have been produced by the acid sap which the roots give off. +(iii) In the soil under ordinary conditions the acid sap performs the same kind of work. + +Conditions Necessary for Absorption.—(1) The air which surrounds the plant must have a certain temperature. This temperature is that at which no evaporation occurs, which is known which no absorption will take place, and a maximum above which this process will cease. Between these two extremes a temperature can be found at which absorption takes place with great vigour, and this temperature is said to be the Optimum temperature. +(2) The soil (or culture solution) must also have a certain temperature before absorption can take place. The roots of a plant take in very little water in winter because the soil is very cold. In summer a larger quantity is taken in because the soil is warmer. +(3) The strength of a culture solution has a very decided effect on absorption. If the solution is very strong, the plant cannot absorb much water, but if it is too weak, the solution is very weak—the condition found in the soil in ordinary circumstances. +Plant to give out Moisture.—Plants not only take in water but they also give it out. This is shown by the atmosphere of forests always being monster than places without vegetation. It has been observed that in a forest, during the active life of a sunflower plant, it will give out 200 times its dry weight of water every day. This is done by means of a long branch, weighing it, and placing it in a dry place. A second weighing in the course of a few hours will show it to have lost weight. +Transpiration.—The way in which the plant gives out the moisture must now be considered. This giving out of moisture by a plant in the form of vapour is called transpiration. It is only those plants of plants which are in contact with the air + +ABSORPTION AND MOVEMENT OF WATER +141 + +which can transpire. The following experiments will show that plants lose water --- + +Expt. 129.--Take three well-developed Mumford plants by their roots, and place them in a dish of water to which a little soap has been added. Pour off the water, and place another with its roots in water, and the third in a dark cupboard. Experiments. + +(i) The plant placed on the table is withered. +(ii) The one in the dark cupboard is in a far better state than the first. +(iii) The plant in water is unerated; the roots have taken water in as fast as they could use it. +(iv) Plants giving out water more actively in a light than in a dark place. + +Expt. 130.--Obtain a potted plant, and cover the soil either with tinfoil or with a sheet of glass. Place this in a dark cupboard; place the pot and its contents on the pan of a scale and weigh. Note-- + +(i) That the pot and its contents lose weight. +(ii) That the soil loses weight, owing to giving out moisture. +(iii) The longer it stays on the scale the lighter it becomes. +(iv) The plant loses weight when it is kept in darkness in winter, using either the electric light or gas. + +Expt. 131.--Obtain a potted plant with tin foil or cardboard base as before, and cover the plant with a bell jar, and place the whole arrangement on a scale. Weigh. + +(i) The inside of the jar is soon covered with moisture. +(ii) The moisture disappears at night. +(iii) The leaves become more moist, i.e., the leaves and stems of the plant. +(iv) The moisture disappears at night because the plant no longer transpires; the moisture is condensed and runs down the jar. + +To prove that a given Green-leaf is losing Moisture + +Expt. 132.--Place some white blotting paper in a weak solution of chloride of lime. Dry these papers either by holding it below a fire or by drying it in an oven. + +Hold a piece of this paper near a leaf which is still on the tree. + +Note-- + +(i) That the paper slowly becomes red; the quicker the colour changes, the more rapidly does the plant lose water. +(ii) A similar piece of paper should be exposed to the air at the same time as the leaf, but without touching it. + +Expt. 133.--There is, as rule, more moisture given off by the under side of a leaf than by the upper. This can be proved by fixing the leaf of a plant on a piece of blotting paper on each face and enclosing between slips of glass. + +The upper face absorbs more moisture; the red colour far more quickly than that on the upper side. + +143 +BOTANY FOR BEGINNERS +CHAP. + +The Organs of Transpiration.—The epidermal tissue of a plant is generally more or less cuticularised (p. 76), and the amount of water vapour which can be given out by the epi- +dermis depends upon the nature of its cuticle. In plants +which are covered with a cuticle, such as well-developed +cacti, very little water vapour is given out. If the cuticle is very thin or absent, as in the case of water plants, the leaves droop +and wilt, and the plant dies. In the case of plants with a +cuticle, those parts of plants which are covered with cork, or +with wax, possess a protection against a too rapid loss of +water. The cork is a protective layer of cork, which prevents loss of water through evaporation. + +The principal organs by which water vapour is transpired by plants are the stomata (p. 94). These are minute pores, +very small, in fact so small that neither dust nor water can pass +through them into the plant; but their enormous numbers more than make up for this defect. It has been estimated that a sun- +flower leaf contains some thirteen million stomata, that an +ordinary leaf of a cabbage may contain eleven million. + +Changes in Size of Stomata.—The size of the stomata +lapse transpiration by changes in their size. They open in bright +weather and close in darkness or in foggy weather. The opening and closing de- +pend on the presence or absence of light. Light only affects the guard-cells (p. 94) contain chlorophyll, and when light shines upon them they become turgid and swell to simulate and form sugar. In this process water is used up, and the cell-sap becomes more concentrated, and the cells contract, so that they move away from the cells in contact with them to the guard cells. As more and more sap is removed from the cells, they become more turgid, or turgid, and being fixed, they shorten and become curved. The small +curved leaf which appears between them is called + +Fig. 151.—Diagram of stomata. + +the stomata close in darkness because then the chloroplasts can no longer assimilate. The sugar which has been previously produced is removed by the movements of the sap, and the sap + +ABSORPTION AND MOVEMENT OF WATER 143 + +in the guard cells returns to its normal strength. Figures 157 and 158 show the opening and closing of the stomata. + +**Lenticels and Transpiration.** The lenticels (p. 108) which open the leaves are situated on the upper side of the leaf, give out water vapour; but the quantity so lost can only be small. The lenticels communicate with the intercellular spaces in the plant, and these spaces are filled with air during the day, but become filled with water during the night. The intercellular spaces in the leaf. In winter the lenticels are closed by ordinary periderm, but they are open in summer. + +**Forces exerted by Transpiring Shoots.** If a branch is cut from a tree, and the cut end is placed in water, it will re- +A diagram showing the shape of a stem when open and closed. +Fig. 159.—Stem in transverse section. The darker lines show the shape of the stem when open, and the lighter lines when closed. (3.) + +main fresh. This shows that the branch can take in water by its cut end. The force which such a branch can exert while actively transpiring can be measured by the following experi- +**Expt. 134.**—Cut a branch from an Oak tree when the leaves are fully developed, and fix it in an air tight manner in a glass tube filled with water. Observe: +(1) The rate at which water rises. +(2) The volume of the water decreases. +(3) The temperature of the water increases. +(iii) This is caused by the suction exerted by the transpiring shoot. +(iv) This is caused by the heat given off by that lost by transpiration. +(vi) That the mercury is forced up the tube by atmospheric pressure. +**Conditions Necessary for Transpiration.** +r. A certain intensity of light ; the stronger the light the greater the transpiration. + +144 +BOTANY FOR BEGINNERS +CHAP. + +(2) The drier the air the more rapid the transpiration ; this is shown by noting how soon a plant withers on a very dry day, and the fresh appearance of a plant on a damp, foggy day. +(3) A windy day is favourable to transpiration. If a plant is placed where the wind is strong, it will lose water faster than if placed where the air is still. +Why Plants Transpire. —The effects of transpiration on the economy of plants are very important and far-reaching. These effects may be summarised as follows :- +(1) Transpiration is the principal way in which plants get rid of the waste products of their metabolism. The solution absorbed by the roots from the soil only contains a small quantity of dissolved salts ; but since very large quantities of the weak solution are lost through the leaves, it is evident that going is still obtaining sufficient mineral matter. +(2) Transpiration plays a very important part in the distribu- +tion of sap throughout the plant. The sap is conveyed to all parts given out through the stomata and bicillae causes a current of sap to be set up from the roots to the leaves, and other parts of the plant. This current is maintained until the results are dissi- +pated by the ascending currents of air brought to all parts of the plant where they are required. +(3) Transpiration also aids the ab- +sorption of water and salts by +the roots. If a plant is growing in a well-watered soil, but its leaves are covered by a bell-jar, the transpiration is continuously increased, and so is absorption of water altogether. If the bell-jar is removed, transpiration increases again, because the water vapour now escapes freely. +Liquid Water Given out by Plants. If one leaf of a plant is cut off, it will be seen that these drops have been deposited on the leaves from + +Fig. 159.—Leaf of +a grass. +159 + +Grasses, Buttercup, Strawberry, etc., and many other +plants are examined on a summer morning, drops of glistening +water will be seen to hang from them. For a long time it was thought that these drops had been deposited on the leaves from + +ABSORPTION AND MOVEMENT OF WATER +145 + +the atmosphere. They were said to be drops of dew. But in far the larger number of cases the water has been pumped out of the water-pores. The roots have taken in an excess of water, which has been forced up the stem to the leaves, and these plants are then said to be "drowning." The water exuded from the water-pores, stomata, or through the epidermis. These drops are evaporated as the sun gains more and more power over the earth's surface. The leaves, being so large and so numerous, which encrusts the leaves, is often left behind, as in the London Pride, Gooseberry, andcurrant. + +EXPT. 137.--Examine a leaf of the Lady's Mantle on a warm summer morning. + +(i) The leaf forms a little cup, and is shaped like a mantle with a mouth. + +(ii) The cup of the leaf is often filled with water which has passed out of the plant. + +(iii) That after emptying the leaf, drops of water ooz out at the end of the leaf-sheath and collect in the bottom of the leaf. + +EXPT. 138.--The leaves of the Arum, also known as the Cuckoo-pint, or Lords and Ladies. +(i) The leaves are very long (from 6 to 10 inches), and are hastate-shaped. +(ii) Drops of water can be seen to fall from the tips of the larger leaves. + +EXPT. 139.--Place a bell-jar over some grass plants which are growing actively. Note: + +(i) That the leaves which were dry to commence with, become in a short time covered with drops of moisture. +(ii) Remove the bell-jar, and the moisture evaporates into the atmosphere. + +Root-Pressure.--If the stem of a vigorously-growing plant, such as the Indian Corn or Sunflower, be cut off just above the ground, and a drop of water be placed on its upper surface, this water is seen to ooze out of the cut vascular bundles. It is also a well-known fact, that if a vine is cut in spring, the cut stem will remain green for several weeks longer than if no cuts are made. If these vines are fully developed and transmitting, it will not bleed. The power which the roots possess of forcing water up the stem is called root-pressure. + +The amount of this pressure can be measured by cutting off the stem of a plant just above the surface of the ground, and + +L + +fixing on the cut end a manometer (Fig. 160). The pressure is often sufficient to force the mercury up the tube to a height of several inches. In the Nettle the root-pressure observed has been found to be about 30 inches, while in the Cabbage it is a port column of mercury about 15 inches high. + +How the Root-Pressure is Set Up.—In spring the root-hairs are very active, taking in large quantities of water from the soil, which passes by osmosis into the cells of the cortex, and when these become filled with water it is forced into the vessels of the xylem. This force with which the water is pumped from the parenchyma cells of the cortex into the xylem is produced by the activity of the root-hairs in absorbing more water than can be stored up in the cells of the root. + +Thus the phenomenon of root-pressure may be explained as follows: The structure of the stem (p. 1420), for it is only when absorption is active that it can take place. + +The water is sucked off the stem of a Plantain or Sunflower just above the soil, and fix to the cut end a hollow glass tube, and fill it with water. The fixing can be done by means of a rubber band round the tube, or by means of the stump and using rubber bands to hold it in place, and to pack the base of the tube with sand. + +The water is pushed higher and higher up the tube against the pres- sure of the atmosphere. The weight of the water lifted will give the amount of root-pressure. + +Expt. 139.—In spring, cut off a branch of the Blackberry. Note— + +(1) A whitish fluid, the sap, oozes out at the cut end. +(2) The sap is forced out by the root-pressure. + +Fig. 160.—Apparatus for measuring root-pressure. + +ABSORPTION AND MOVEMENT OF WATER +147 + +How the Water Travels from the Roots to the Leaves. +The water which, as we have seen, is forced into the xylem vessels of the root finds its way to the leaves (as far as we know at present) up the interior of the vessels of the stem and branches. The leaves are so large that they blocked up the interior of the vessels with paraffin-wax, only a little water found its way up the stem, and the leaves on the branch were dry. This shows that there must be a large quantity of water which the plant requires to pass either up the parenchyma cells, or through the cell walls. The water is able to move faster up the interior of the vessels than in any other direction. + +The Transpiration Current.--The current of water which passes up the stem from the roots to the leaves, is made good that lost by transpiration, is called the transpiration current. This current travels up the stem of a woody plant, but only through the outer and younger rings (p. 107). The heart wood of an old tree never takes part in the conduction of water, but only the newer rings of the sap wood. The reason why this transpiration current ascends as it does in some trees to a height of over a hundred feet is not fully understood, and + + +A diagram illustrating how the water moves up a stem. A normal transpiration current is shown in three stages: 1st, water enters the leaf; 2nd, water evaporates from the leaf; 3rd, water returns to the stem. + + +Fig. 105.--Diagram illustrating how the water moves up a stem. A normal transpiration current is shown in three stages: 1st, water enters the leaf; 2nd, water evaporates from the leaf; 3rd, water returns to the stem. + +L + +148 +BOTANY FOR BEGINNERS +CHAT. + +is one of the problems of plant physiology which requires solving. +The following experiments will demonstrate how the sap travels in woody plants. + +EXPT. 140.—A woody plant, such as an Oak, which is growing +in a wood, is cut down to the ground, and the bark removed as far +as the new wood, i.e., cut away the bark cortex and phloem, and +pack the wounds with cotton wool to prevent the entrance of +fungus. A few days later, the new wood has grown up through +the bark and cortex. Note— + +The bark of the tree, which has only a ring of tissue removed, +down to the new wood, are still green and fresh. +The phloem of the tree, which has been cut away, new wood removed, +have flaged! they ultimately die. +(1) The phloem is a good that laid by transpiration, travels in the new wood, but neither in the cortex nor in the bark. +EXPT. 141.—In many parts of the country old trees may be seen which have been felled and left standing for some time. When such a +plant when a tree is encountered, the following observations should be made. Note— + +(1) That the leaves are green and fresh. +(2) That water can be drawn off with a pipe. This can only take place through the new wood, because the heart wood and the outer part of the tree have decayed. The water travels only through the new wood. + +How the Elaborated Sap Travels in Plants.—The sap which is acted on in the leaves by the chlorophyll and proto- +plasm, is called protoplasmic sap. The sap which is acted on by +called elaborated sap. This is distributed to those parts of +the plant where growth is going on, or where reserve material +is stored up. How does this sap travel? The xylem is filled with +sap as soon as it is formed. The xylem will be found distributed over the upper surface of the leaf, and the phloem on the under side. +The xylem brings water and minerals in solution to the cells of +the leaf. As these cells grow larger, they require more food for +the fit nourishment of the plant, it is carried away down the +phloem. Different materials are produced in the leaf by the activity of chlorophyll. These materials are transported by the +can be divided into proteins, fats, and carbohydrates (p. 87-). +Each of these is distributed in a different way throughout the +plant. The protein substances in the elaborated sap travel + +ABSORPTION AND MOVEMENT OF WATER 149 + +along the sieve tube of the phloem, and from cell to cell by osmosis, to those parts of the plant where they are needed. + +The carbohydrate sugars (sugars) travel in solution along the parenchyma cells of the leaf, through the vascular bundles in the leaf and belong to the cortex of the stem. + +The needs of the various parts of the plant cause the current to move from one part to another. The current is built up in the formation of new cells, or is being stored up as reserve material. + +EXPT. 142.—From the plant used for Experiment 130, cut away from the base about two inches of stem, leaving a short piece at the top. Note: + +The branch below the cut will not increase in size unless ethylene gas is brought from some other part of the plant, and, as a rule, this does not happen. + +EXPT. 143.—Remove a branch from a woody plant, such as the Beech, and at about nine inches from the base remove a ring of bark with a knife. Remove all roots from around the branch, and place it in water without injuring it. Note— + +(i) The branch will grow outwards and upwards. It leaves the place where the ring of tissue has been removed. + +(ii) The branch will not grow outwards on that portion below the wound, because no ethylene gas can pass through the wound because of its impermeability. + +(iii) The branch from the piece which was placed in water without being injured produces roots from the tip of the stem. + +SUMMARY. + +Absorption of Water and Minerals.—All materials (with the exception of carbon) which plants require for their growth are taken in by the root system. These materials are absorbed by osmosis. + +Osmosis.—The mixing of fluids through a permeable membrane is called osmosis. In order that this process be necessary for the fluids to have different densities. + +The absorption of water by roots can dissolve some of the insoluble con- +stituents of the soil. + +Conditions necessary for absorption. + +(1) The soil must be moist. +(2) The soil must have a certain temperature. +(3) The soil or solution in which the plant is growing must also have a certain temperature. +(4) The strength of the solution has a decided effect on absorption. + +For example, in an atmosphere containing 50% oxygen and 50% moisture, an Oak tree gives out many gallons of water on + +150 +BOTANY FOR BEGINNERS +CHAP. + +bright summer days; a Sunflower during its active life gives out 300 times its dry weight of water. +Transpiration is the giving off of water vapor by a plant. Only those parts of a plant which have the atmosphere can transpire. +The Organs of Transpiration. --Stemlets and leaflets are the organs by which plants lose water. The stemlets are the organs that give off water. +Condensation favourable to Transpiration.--(1) A certain intensity of light; (2) a dry atmosphere; (3) a windy day. +Water is given off by the leaves in two ways: (a) through excess of water taken in by the roots; (b) and the distribution of salts throughout the plant; (c) through the stomata. +Liquid Water given out by Plants.--Plants like the Lady's Mantle, Buttercup, and Ammox give out liquid water through water pores, stomata, or stomata. +Root Pressure is the pressure which roots possess of forcing water up through them. +New Root Pressure is Set Up.--Root-hairs are very active in sipping, and the spaces between them are filled with water. The water from the cells exudes into the vessels of the xylem, and so on up to the leaves. +Water Travels in Plants up the interior of the vessels of the new wood. +The Transpiration Current is the current of water which passes up the stem to make good that lost by transpiration. It passes up either as separate vacuoles or as separate vacuolar bundles (branching leaves). +Stomata.--The pores in the leaves are called stomata. They are cup-shaped and protoplasmic in the leaves. It travels in the following way:--(1) The protoplasm of the epidermis cells moves towards the stomata; (2) The protoplasmic strands within the parenchyma cells round the vascular bundles; (3) a slow movement occurs from cell to cell to make good the loss due to drought. +Questions on Chapter XL. + +(1) What is one of its food does a green plant obtain by means of Roots? How does it absorb food? (187) +(2) What do you know about: +(a) The materials found in a fertile soil? +(b) The materials found in a barren soil? +(c) The particles of a soil? +(d) The way in which water travels in a soil? +(3) Define transpiration. Explain what part this comiosis plays in the nutrition of a plant. +(4) What conditions are necessary for absorption? +(5) What is meant by "transpiration"? Explain the relation between the structure and functions of a root. (189) +(6) How do plants get their food up on a hot day and recover their freshness in the evening. (189g) +(7) What is the "transpiration current"? State by what time it + +ABSORPTION AND MOVEMENT OF WATER 151 + +travels in the plant, and describe an experiment proving your statement. +(89p.) + +(1) What is the chief function of the wood? Give experimental evidence in support of your answer. (89p.) + +(2) What is meant by "root-pressure"? What manifestation of it occurs in nature? (89p.) + +(3) The root is the shortest organs of roots, and of the periphery of absorption. (89p.) + +(11) The trunk of an Oak tree, when in full leaf, is sealed all round so that no water can escape. How does this happen? Describe the effect of this operation. (89p.) + +(12) What is the effect of a tight ligature upon a growing based stem? + +(13) What is meant by transpiration? In what circumstances does plants transpire most? Give experiments which demonstrate how transpiration may be prevented. (89p.) + +(14) Why does a branch when removed from a plant begin to flag? +How may this be prevented? (895.) + +A diagram showing the structure of a plant, including roots, stems, leaves, and flowers. +Watermarked text: "ABSORPTION AND MOVEMENT OF WATER" "151" "Page number" "XI" "ABSORPTION AND MOVEMENT OF WATER" "151" "Page number" "XI" "ABSORPTION AND MOVEMENT OF WATER" "151" "Page number" "XI" "ABSORPTION AND MOVEMENT OF WATER" "151" "Page number" "XI" "ABSORPTION AND MOVEMENT OF WATER" "151" "Page number" "XI" "ABSORPTION AND MOVEMENT OF WATER" "151" "Page number" "XI" "ABSORPTION AND MOVEMENT OF WATER" "151" "Page number" "XI" "ABSORPTION AND MOVEMENT OF WATER" "151" "Page number" "XI" "ABSORPTION AND MOVEMENT OF WATER" "151" "Page number" "XI" "ABSORPTION AND MOVEMENT OF WATER" "151" "Page number" "XI" "ABSORPTION AND MOVEMENT OF WATER" "151" "Page number" "XI" "ABSORPTION AND MOVEMENT OF WATER" "151" "Page number" "XI" "ABSORPTION AND MOVEMENT OF WATER" "151" "Page number" "XI" "ABSORPTION AND MOVEMENT OF WATER" "151" "Page number" "XI" "ABSORPTION AND MOVEMENT OF WATER" "151" "Page number" "XI" + +CHAPTER XII + +THE PHYSIOLOGY OF GROWTH AND MOVEMENT + +Growth.—The permanent change of form which takes place in living plants is called growth. The change of size in a dead seed which takes place when it is placed in water is not a permanent change, but only a temporary one, owing to its return to original size. On the other hand, if a living seed is supplied with water, the young embryo it contains commences to develop. Root, shoot, and leaves begin to grow, and the plant assumes a characteristic shape and size that takes place, or in other words, it grows. It is only living things which can grow. + +Conditions necessary for Growth.— + +1. Heat. The plant and surrounding air must be at a certain temperature. In winter the temperature of the soil is too low for absorption of heat by the plant roots. In summer the lowest temperature at which plants can grow is said to be the minimum temperature of growth. There is a temperature above which all growth ceases. The cessation of growth may be caused either by the activity of the roots being arrested, or by the cells losing water so that they are no longer turgid. The highest temperature at which plants can grow varies according to the species of plant. For example, the temperatures of extreme temperature above and below which no growth can take place vary for different plants. Between the minimum and maximum temperatures of growth there is usually a range in which growth best; this is said to be the optimum temperature for growth. +2. Water.—No plant can grow without water, since its substance is largely made up of water. Water is also necessary as a medium for carrying nutritive materials to some parts of the plant where growth is taking place, and it is + +CH. XII PHYSIOLOGY OF GROWTH AND MOVEMENT 153 + +the means by which the green parts of plants are kept fresh, and the cells turgid. + +2. OXYGEN.--Those parts of the plants where growth is produced require oxygen for without it no energy can be produced. No growth can take place without energy. Energy is produced when a plant respirs (p. 125). + +3. Food.--The presence of suitable food materials present: Food may either be stored up in seeds, or it may be taken along with water from the soil, or be obtained by the leaves. + +4. Cells in an Embryonic Condition.--The cells of some parts of the plant must be in such a condition that they can divide rapidly. + +5. Light.--While light is not absolutely essential for growth, it is still necessary for healthy growth. Plants will grow faster in the light than in the light as well seen in the case of Rhubarb, which grows very slowly in the dark, but fast in the light and slender stems. When grown in the light the stem of Rhubarb is short and thick, and its leaves large. Speaking generally, all plants which have long stems and leaves, such as grasses, have soft stems, which are very much elongated, and of a pale colour. The leaf-blades, in similar circumstances, are small, and their edges are serrated, and their walls are thinner, and contain more water than those grown in the light, or light may be said to retard growth. + +6. The stems of plants grow together so that light cannot pass between the plants, the stems become long and so slender that they can no longer support the ears of corn, and the stems become brittle and break off at the joints like a bundle of wheat. It can be prevented by leaving a sufficient space between the rows to enable light to pass between the plants, when the growth is rapid. + +The rapid growth of shoots produced from bulbs, tubers, rhizomes, and seeds is especially valuable, for the light is thus readily available, and the plants are then capable of independent nutrition. + +Plants grow more rapidly during the night than day. During the day assimilation goes on and the materials then stored are used during darkness in producing a permanent change in the plant. + +154 +BOTANY FOR BEGINNERS +CHAP. + +EXPT. 144.—Fill two pot plants with soil, and sow a few Mustard seeds in each. Keep the soil moist. Place one pot in a window and observe it daily. The other will remain in a dark cupboard. Measure the length of the plants in each pot from the time they germinate until they die. +(i) The plants kept in the dark cupboard are yellow in colour; those exposed to light are green. +(ii) Those grown in the dark increase in length nearly three times as much as those grown in light. +(iii) The leaves of the plants grown in the dark are very small, but those grown in light are large. +(iv) The plants kept in the dark begin to droop and soon die; those grown in light continue to grow vigorously. +(v) The plants in the dark are often attacked by fungi. +(vi) Light is necessary for the healthy growth of plants, but they cannot flourish without it. + +Growth in Length of Plants.—At the apex of a shoot or root are two zones of growth. At the extreme apex of the stem there is a zone of cell division, which is called the apical meristem. Just behind this region the cells increase in size, but little cell division takes place. +Most plants show at some time or time show a change in the vigour of the growing point. If a plant like the Dreadnought is examined, the nodes at the base are seen to be crowded together; that is, they are close together. As we move up the stem the nodes are larger, while again towards the apex the nodes are crowded together and the internodes are short. The variation in the length of the internodes depends upon the strength of the growing point. When a plant is growing vigorously its growing point is strong and it produces short internodes; as it gains strength, longer and longer internodes are produced. Later, its strength or activity decreases and it produces long internodes until at last the period of growth has ceased. Similarly in the life of most plants there is a grand period of growth. + +Measurements made on several varieties of Indian Corn, show this increase in vigour of the growing point to perfection. If the plume of a germinating seed of Indian Corn be examined it will be found that when measured from one end to another meter of a mature stem be measured it will be found to be many times larger. How has this increase in size been produced? The growing point at first produces short internodes; but as it gains strength it produces longer ones, and so on until at last it produces its greatest size. A larger and larger stem was produced. +But, here again, the vigour of the growing point declines later in life and the stem produced has a smaller diameter. + +xii PHYSIOLOGY OF GROWTH AND MOVEMENT 155 + +Expt. 146—Obtain a well-developed Dendrite and examine it. +Note— + +(i) The leaves are crowded together at the base and apex; between these two regions they are further apart. +(ii) The leaves are produced in two series in pairs; where the inter- +nodes are long, the leaves are produced in greater distance apart. +(iii) That part of the stem where the internodes are longest were probably the first to grow. + +Expt. 147—Sow a few seeds of the Indian Corn in a pot. Keep +the soil moist and warm, and exposed to light in a window. Measure +at intervals the length of the plant, its diameter, and thickness of the +seedlings from time to time. Measure and record: + +(i) The circumference of the plantule when it first appears above the +ground. +(ii) The length of the plantule when it first appears above the ground. +(iii) Repeat the above measurements every day during the growth of the +plantule. +(iv) Preserve the record of the series of measurements for future reference. + +Expt. 148—Germinate a Bean seed, and when the radicle is well +developed wash it. Measure off half an inch from the tip of the +radicle and cut it into two pieces. Place one piece in a test-tube, +Pass a fish hook through the seed, and suspend it to a cork in a bottle +which contains a little water. Examine at the end of twenty-four hours. +Note— + +(i) The amount of growth. Measure from the tip of the radicle to +the point where it was cut. +(ii) The general period of growth is well illustrated by the amount of +elongation taking place in each part of the plantule during this time. +(iii) The differences in the amount of growth in the different parts of +the plantule may be seen by comparing their lengths after periods of +elongation take place in the zone where the cells are increasing in size. + +Irritability—Living organism possesses many properties, but one of the most important is its power of responding to external stimuli. This property is called irritability or sensiveness. The response to these external agencies very commonly takes place in two ways: + +Growing organs possess the property of irritability to a far greater extent than the older parts of plants. The irritability of growing organs must be distinguished from the irritability of mature organs. + +156 +BOTANY FOR BEGINNERS +CHA. +THE IRRITABILITY OF GROWING ORGANS. +The principal stimuli which act on the growing organs and produce movements are light, gravitation and water. The agencies which cause these movements and the movements which they produce, will here be considered. +The Action of Light on the direction of Growth.- +The importance of light to the growth of plants has been shown. We have seen how necessary it is for assimilation, and for the healthy growth of a plant. The various parts of plants react in different ways to light. In some cases a portion of a plant generally turns towards the light, while those parts which under normal conditions develop in the dark, turn from it. In the case of leaves, the light is necessary for their full development, but leaf-butter can grow without light. +Heliotropism.-The action of light is well shown by win- +dow-plants. The stems of such plants are not erect as in the ordinary case, but bend towards the window when opened. The turning of a portion of a plant either towards or away from the light is called heliotropism. +Positive Heliotropism.-The portions of a plant which turn towards the light are said to be positively heliotropic. The stems and leaf-stalks incline towards the source of illumin- +ation, and the leaves turn so that they receive more rays of light. But the leaf-blades arrange themselves at right angles to the illumination and so receive the maximum amount of light. +Negative Heliotropism.-The portions of a plant which turn from the light are said to be negatively heliotropic. Roots, rhizomes, and bulbs turn from the light and are conse- +quently negatively heliotropic. Aerial roots like those of the Ficus are also negatively heliotropic. +Expt. 148.-Place a pot containing a Castor Oil plant on a window sill, and observe it from day to day. Note: +(i) That when the sun is behind the plant, the sun-leaf bends towards it; the side-leaves arrange themselves at right angles to the window. +(ii) That when the sun is in front of the plant, all leaves move round until they occupy their old position. +Expt. 149.-Examine a piece of Ivy which is clinging to the wall or to the ceiling. Note: +(i) Most of the clinging roots are developed on the shady side of the stem. +(ii) The roots developing in the light are turned away from it. + +A diagram showing a plant with its leaves turning towards or away from light. + +KII PHYSIOLOGY OF GROWTH AND MOVEMENT 157 + +Expt. 120.—Obtain a box which will just cover a pot of Mark. +Cover the pot with the box, and so arrange matters that the light from a window shall fall on the plant in twenty-four hours. +Note— +(i) The plant turns towards the light. +Turn the box so that the light can only shine into one corner. +(ii) On the following day the plants will have turned again to seek the light. +Turn the box so that the plant can only receive light from the room. +(iii) The plants will turn away from the light. +Plants like Mark are light-fishers. They always arrange them- +selves so as to receive the maximum amount of light. + +Constituents of White Light which Produce Heliotropism—if a plant is grown so that the red and yellow rays of the spectrum (p. 123) can fall on it, there is neither red nor yellow light falling on it. But if we mix together the influence of the blue and violet rays nearly as much curvatures take place as in white light. + +Expt. 121.—Obtain two boxes similar to the one used in Experiment 120, and cover each with a sheet of glass. Then see that they can have slips of glass inserted. Germinate three pots of Cress and mark them A, B, C. Put A in a dark room, B in a room with white light. Cover both with a box and slide a piece of glass into position, so that red light falls on A and white light on B. Now put C in a dark room and slide a piece of glass into position, so that blue rays can only pass to the plants. Note— + +(1) The plants put A turn towards the window in the same way as the Mark plant. + +(2) The plants in pot B grow erect; they do not curve in any direction. + +(3) The plants in pot C curve towards the source of light just as do the plants in pot A. + +Experimental Results.—It must consequently be con- +cluded: + +(1) That plants growing in a window, and more strongly +illuminated on one side than the other, bend towards the source of +light. + +(2) That plants which receive only red rays grow erect, and do not curve at all; but those which receive blue rays grow as +they would in the open air. The rays from the red end of +the spectrum are not instrumental in producing curvature. + +138 +BOTANY FOR BEGINNERS +CHA.F. + +(3) That plants which receive blue rays bend towards the side where the strongest light falls, just as plants do which grow in white light. +(4) That the curvature of leaves in heliotropic organs is due to the rays of the blue of the spectrum. + +**Why Heliotropic Movements take Place.** The movements which plant organs show when acted on by light is different from that which takes place in animals. In the case of the side in the shade grows faster than that exposed to the brightest light, or a different distribution of water occurs in the cells of the organs. It must be distinctly understood, that no matter what may be the cause of this difference in growth, architecture, it is the protoplasm of the plant cells which responds to it. + +**Geotropism.** We have seen that most shoots either grow erect or droop downwards according to their position with respect to the light. There is, however, another external agency in addition to light, to which acts on various parts of plants. This force produces a bending of the shoot towards the earth. The organs of plants and is spoken of as **gravitation**. + +The property which enables plants to take up a definite position under the influence of gravity is called **geotropism**. Some organs grow in opposite to the attractive force of gravity, others grow in the same direction as gravitation acts. As in the case of heliotropism, we use the terms negative and positive to describe these two types of geotropism. + +**Positive Geotropism.** Those parts of plants which grow towards the centre of the earth are said to be positively geotropic. The roots and stems of all plants are surrounded by a sheath, grow downwards and are positively geotropic. Lateral roots and stems grow outwards, and are described as being negatively geotropic. The lateral roots and stems of some plants are injured, and one of the secondary roots has developed a posi- +tively geotropic growth. + +**Negative Geotropism.** All those parts of a plant which grow upwards or away from the centre of the earth are said to be negatively geotropic. This is the rule with erect stems, flower-stems, and a few leaves. + +A leaf sheath will probably know, by gravitation is meant the mutual attraction between bodies having mass. The attraction between the earth and bodies near it gives rise to weight of bodies. + +XII PHYSIOLOGY OF GROWTH AND MOVEMENT 159 + +Exr.: 125. - Germinate a few Pans in damp sawdust. Place one on damp soil. Place another with the radicle and plumule in a horizontal position. + +(1) The radicle of the Pan grows downwards and the plumule upwards. + +(2) The plumule of the Pan grows on the piece of wood, and then upwards, but the root grows downwards. The piece of glass until it touches the edge, when it turns to grow at right angle with the stem and then grows down- wards. + +(3) (ii) This shows that the plant is negatively gravitropic. + +Exr.: 126. - Make a hole in the bottom of a pan and turn up the drainage. This can be done by striking a block of wood with a sharp pick. + +The plant will crack, but if it holds together it will do. Fill with water and put in a quick growing plant it will grow up. + +Note: - The plant will be seen near the glass (Fig. 161), or, if they should appear there, they will soon bend away from the light. + +(4) Examine the paper to prevent the light from affecting the roots. Examine in a few days. + +(5) The Pan is completely filled with roots. + +(6) If the Plant and seed are turned out, and a sharp knife is used to + +A photograph of a plant grown in a container showing the distribution of the roots. The white spots indicate where the growth of the plant's mantle was covered with sand or clay. The plant has both roots and shoots. + +fig. 160 - Photograph of a plant grown in a container to show the distribution of the roots. The white spots indicate where the growth of the plant's mantle was covered with sand or clay. The plant has both roots and shoots. + +160 +BOTANY FOR BEGINNERS +CHAP. + +cut a slice of soil away near the centre, it will be found full of roots with the tap-root growing downwards. + +(iv) This shows that the ordinary roots are negatively heliostic and that the root system is not a simple one. + +Hydrotrophyism.--It has already been seen (p. 50) that roots growing in dry soil are attracted by moisture. The move- +ment of any part of a plant towards moisture is termed hydro- +trophy. It is evident that this property is a direct result of contact +with the other organs of plants. + +Movements Caused by Contact.--Just as animal bodies respond to light and sound so do plant bodies. This is well shown in the case of climbing organs (p. 26). When a tendril comes in contact with a solid body the side of the tendril which is in contact grows more quickly than the side away from the object. This produces an elongation of the side away from the object and causes the tendril to curve and twine round the object. + +THE IRRITABILITY OF MATURE ORGANS + +Special Cases.--Most full grown organs are incapable of moving, but the organs of a few plants are endowed with the power of vigorous movement. These movements are due to changes in the contents of the cells of which these organs contain. When cells are full of water, it presses on the elastic walls and they become greatly distended, their cavities becom- +ing enlarged. If the cell is empty, it shrinks and its walls +are diminished. It is to the changes in the size of the cells of an organ that the movements under consideration are due. + +The amount of water in the cells depends upon the temperature and amount of light which they receive. The change in the position of leaves and the opening and closing of flowers are due to changes in temperature and light received by each leaf or flower. The turgidity, depending as it does upon the amount of water absorbed, is evidently produced by the amount of light and temperature. Many flowers and leaves show a periodic movement. + +The Opening and Closing of Flowers.--Many flowers and some inflorescences (p. 140) change their position from day + +XII PHYSIOLOGY OF GROWTH AND MOVEMENT 161 + +to night. It is in a general rule that flowers are open during light and closed at night; but a few open at night and close during the day. The closing of the flowers during darkness is called the diurnal rhythm. + +**Expt. 154.—Collect a few flowers of the Dandelion, and place them in a tin so that they receive no light. Note—(a) The flowers remain open all night. (b) Now place their cut ends in water and expose them to a bright light. Note—(c) The flowers close immediately after exposure to light. + +This shows that the amount of light which they receive causes them to close. + +**Expt. 155.—Hanging a Tulip plant with fully developed flowers, which are closed, into a room warm. Note—(a) The temperature is about ten degrees Fahrenheit higher than the external air whence the plant was obtained, the flowers remain open. + +Now expose the flowers to a lower temperature, either by placing them in a cold room or by placing them in a glass with a mixture of salt and ice. + +The flowers will close. The closing of the flowers is due to the decrease in the amount of heat which they receive. + +The **Sleep of Leaves** —If the compound leaves of the plant are placed in a dark room, they remain closed until they are found to be folded so as to expose the least amount of surface to the atmosphere. If the same leaves are noticed at noon they are found to be open. + +**The Utility of Plant Movements—the heliotropic and geotropic movements of organs place them in the most favourable position for performing their functions.** + +To receive maximum benefit from sunlight, exposed to the rays of light, they receive the maximum amount of light and energy, and are thus able to assimilate to perfection. The primary cotyledons of seedlings grow towards the light, and thus into new soil from which food is obtained. The primary stem grows erect, places the aerial organs in a good position for receiving light, and thus enables them to perform their functions. Thus, when placed in a good position to obtain food, and to fix the plant firmly in the soil. The flowers close at night to protect the internal parts from being damaged by rain and dew, and prevent them from being washed by rain and dew. They open in warm sunshine so that insects can visit them, and close in the cold to prevent loss of heat. Those flowers which open during dark- +ness and close during light are visited by night-flying insects. + +162 +BOTANV FOR BEGINNERS +CHA. +The change from the diurnal to the nocturnal position, which many leaves undergo, protects them from rain, snow, hail, changes in temperature, and prevents loss of heat by radiation. The leaves are folded so as to expose the minimum amount of surface to the air during the day and to cover as much possible during the diurnal as much surface as possible is exposed for assimilation. + +SUMMARY. +**Growth** means a permanent change of form. It is only living things which grow. +**Conditiona necessaria for Growth.** (1) A certain temperature which varies with the species must be maintained at all times. This temperaure below which no growth can take place, and a maximum above which no growth can be arrested. Between these points the optimum temperature occurs. +(2) Light must be present, because it enters into the composition of the protoplasm. +(3) Oxygen is necessary for most plants. +(4) Carbon dioxide is necessary for growth. +(5) Light is necessary for the healthy growth of all green plants. +Light is a necessary condition for **irritability**. Irritability means the property of protoplasts to respond to external stimuli. In this respect light is superior to heat, cold, gravity, and moisture are the principal agents which produce movement. + +The Action of Light on Growing Organisms. **Heliotropism** refers to the power of turning either towards the light or away from it which plants possess. The leaves of Heliotrope turn towards the light and become positively heliotropic. Roots, rhizomes, and bulbs turn from the light and become negatively heliotropic. +**Heliotropic movements** take place as a result of changes in the length of daylight and darkness. These changes are due to the action of photosynthesis. + +**Growth** has another property which enables the organs of plants to take up a definite position in regard to gravitation. +**Movements caused by Gravity.** The roots of plants grow downwards with such rapidity that those which touch it has its growth arrested, and the opposite side grows more quickly. This causes curvature, and eventually results in a vertical position. +The Sleepers of Flowers and Leaves. Many flowers and leaves change their position during the night. They may be moved by mechanical changes in the amount of water which they contain or by the cells of various parts of foliage being filled with gas. + +The Utility of the Movements. All the movements which the various parts of plants perform are to bring the plants into touch with their surroundings. + +A diagram showing different positions of leaves and stems in relation to light. + +xii PHYSIOLOGY OF GROWTH AND MOVEMENT 163 + +QUESTIONS ON CHAPTER XII. + +(1) Define the term growth. What conditions are necessary for growth? + +(2) Why does Rhubarb grow faster in the dark than in the light ? + +(3) Give an account of an experiment which proves that plants grow more rapidly when they are exposed to red light than to green light. + +(4) Explain, and illustrate by an experiment what is meant by "a gradual change" in the direction of growth. + +(5) The protoplasm is said to possess the property of initiality. Explain this statement. + +(6) Why do the stems and leaves of window plants take up a definite position in relation to the light? (1897.) + +(7) Explain the term heterotropism. Aerial stems are said to be heterotropically curved towards the light. How is this possible ? (1897.) + +(8) A plant is covered with a blue glass. How will its method of growth be affected? (1897.) Under red glass? + +(9) Explain why it is that when a seed germinates, the stem grows upwards and the root downwards. (1890 and 1897.) + +(10) Explain how the rays of light upon the direction of growth of stems and of roots. (1891.) + +(11) Explain how the direction of growth of stems and leaves is changed by exposure to light. (1896.) + +(12) The stomata are open in the light and closed during darkness. Explain how this change is produced, and of what service it is to the flower. + +M 2 + +CHAPTER XIII + +FLOWER AND INFLORESCENCES + +Floral Leaves.---In addition to the foliage leaves p. 31, stipules (p. 45), and bracts (p. 46), which have already been dealt with, certain modified leaves which go to build up the flowers of a flowering plant, and are called floral leaves, now come into consideration. The successive whorls or rings of flowers are seen commencing with the external whorl, as follows: + +1. The Calyx, built up of separate segments, receive the name of sepals. Each sepal is a leaf, and is, as a general rule, green. + +2. The Corolla, made up of petals. Each petal is also a modified leaf, which may be brightly coloured and of a peculiar shape. + +3. The Androecium is built up of stamens which form the male organs of reproduction and produce a substance called pollen. Each stamen is like a sepal and petal, a modified leaf; it + +A diagram of flowers in longitudinal section. +Fig. + +a. calyx ; b. corolla ; c. androecium ; d. gynaeceum. +e. stamens. +f. pistil. +g. ovary. +h. ovule. +i. placenta. +j. placenta. +k. placenta. +l. placenta. +m. placenta. +n. placenta. +o. placenta. +p. placenta. +q. placenta. +r. placenta. +s. placenta. +t. placenta. +u. placenta. +v. placenta. +w. placenta. +x. placenta. +y. placenta. +z. placenta. + +The Androecium is built up of stamens which form the male organs of reproduction and produce a substance called pollen. Each stamen is like a sepal and petal, a modified leaf; it + +CH. XIII +FLOWER AND INFLORESCENCES +165 + +performs a special work in connection with the reproduction of plants. + +4—the Gymnocarp, or pistil, is built up of carpels. The perianth is wanting, but the ovary, which occupies the centre of the flower. It produces ovules, which under healthy conditions form the future seeds. The following experiments will make clear what is meant by floral leaves. + +Experiments on the Gymnocarp. + +(i) The calyx on the outside of the flower. In this case it is built up of four sepals, each of which is long and hairy. The two inner sepals are green, and the two outer sepals are brownish-red in colour, can be pulled off without tearing it from its frame. + +(ii) Standing just within the calyx, and alternating with the sepals, four stamens are found. These are called the filaments of the corolla. The petals are arranged in the form of a cross and are the base of the flower. + +(iii) Within the corolla six stamina occur. Four are long and two short. The long ones are called stamens proper, and the short ones—hairs—the anther. Upon the anther it contains a number of microscopical pollen grains. + +(iv) The centre of the flower is occupied by two carpels joined together, which form the pistil, and is divided at the apex into two lobes. The lower lobe is called the stigma, and the upper lobe pistil is called the corolla. The lobes at the apex of the corolla form the petals. + +(v) Open the corolla: a number of rounded bodies are seen—the ovaries. + +EXPT. 157.—Examine the flower of a Buttercup. Note— + +(i) The five apicals (green and leaf-like in appearance) on the outside forming a cup-shaped receptacle. + +(ii) Five yellow petals, containing the corolla, are found just within the receptacle. + +(iii) A number of yellow stamens, each consisting of a filament and an anther. + +(iv) Many small green discs—not united together as in the wall-flower—make up the pistil. Each carpel possesses at its base a swollen portion, which is called a placenta, upon which seeds can be dis- tinguished. + +(v) In each ovary a small egg-shaped ovule is to be found. + +Flower.—The following reasons lead us to believe that a flower is a modified shoot. +1.—The flowers are produced either at the apex of a shoot or in the axil of foliage-leaves. This is just in position in which we find branches or shoots (p. 16). + +A diagram showing a flower with sepals, petals, stamens, and pistil. + +166 +BOTANY FOR BEGINNERS +CHAP. + +2. The floral leaves are arranged either in a lateral (p. 17) or in a spiral (p. 37) manner. This is just what we find in the case of foliage leaves (p. 36-7). +3. The floral leaves are very often leaf-like in form, markings, and colour. +4. In many cases the intermediate forms between floral leaves and foliage leaves can be seen on one plant. Thus, in the White Water-Lily there are numerous intermediate forms between carpel-like and leaf-like flowers (Fig. 165). In the Rose, too, all the various stages between foliage leaves and carpels can be made out. +5. In some cases, also, change of surroundings, the floral leaves may become changed. Thus, in the cultivated Rose, the stamens and carpels have been converted into petals. In some cases, however, can be collected possessing green leaves instead of carpellary ones. +A flower is a branch which has become modified for the special work of producing seeds for the reproduction of its kind. + +**Inflorescence.**—An inflorescence is a collection of flowers produced from a common stalk. The common stalk upon which these flowers grow is called a peduncle (Fig. 164). If the flowers possess stalks which connect them to the peduncle the stalks are called pedicels. When the flowers spring from the peduncle without stalks they are said to be sessile. +Many inflorescences are produced in the axils of leaves, with the result that the flowers are usually found at the apex of a shoot of the flower is said to be terminal. +**Indefinite Inflorescences.**—If the flowers at the base of an inflorescence are produced by means of lateral buds of the same plant, such an inflorescence is called indefinite. In such an inflorescence the apex keeps on producing flowers, and we cannot tell where it is going to stop flowering. +**Spike.**—If the flowers are produced by indefinite inflorescences, all bearing a certain relation to one another. When the flowers are arranged on the peduncle in a sessile manner, i.e., without stalks, the inflorescence is said to be a spike. Examples: Liliums or Lilies, Bistort, and Verbena (Fig. 165). + +A diagram showing different types of inflorescences. + +FLOWER AND INFLORESCENCES 167 + +Raceme. --When the flowers are connected to the peduncle by pedicels they form a raceme. This is a very common form + +A diagram of Lodeolias. A, raceme ; B, pedicel ; C, spike ; D, umbel ; E, head. +Fig. 164.--Diagram of Lodeolias. + +Spikes of Bunter. (One-half natural size.) +Fig. 165.--Raceme of Wild Hyacinth. (One-half natural size.) + +Pedicel of Oats. (Reduced.) +Fig. 166.--Pedicel of Oats. + +of inflorescence. Examples--Wallflower, Foxglove, and Hyacinth. (Fig. 166). + +168 +BOTANY FOR BEGINNERS +CNAE. + +**Panicle.**—When the pedicels themselves branch, so that there are two or more flowers produced from a single pedicel, a **panicle** is formed. Examples—Rhubarb, Oats, (Fig. 167.) + +**Corymb.**—When the pedicels are produced at different levels, and are of different length, all the flowers being thus brought together in one head, an inflorescence is called a **corymb**. Example—Candy Tuff. (Fig. 168.) + +**Simple Umbel.**—If all the pedicels spring from the same point of the peduncle and the flowers are brought to the same level, a **simple umbel** is formed. Examples—Cherry and Coslip. (Fig. 169.) + +**Compound Umbel.**—If all the pedicels spring from the same point of the peduncle, and branch so as to bring all the flowers together in one head, this is called a **compound umbel**. Examples—Fool's Parsley, Carrot, and Hem-ock. (Fig. 170.) + +**Head capitulum.**—An inflorescence in which the peduncle is shortened and flattened out, and the flowers are fixed to it either by pedicels or are sessile, is called a head or capitulum. The flattened-out peduncle is called a common + +A B +Fig. 169.—A, Corymb of Candy Tuff ; Fig. 169., Simple umbel of Coslip. +(R, section of.) + +xiii FLOWER AND INFLORESCENCES 169 + +** receptacle.** The capitulum is very common in the order of plants called the Compositae. The florets of the head open on the outside first, the inner ones opening last. Examples—Daisy, Dandelion, and Clover. (Fig. 172.) + +Fig. 171.—Compound umbel of lowest Cusly. +Fig. 172.—Enlarged view of compound umbel of lowest Cusly. +Fig. 173.—Head of Clover. (Line-both size.) + +**Exr.t. 150.—Examine the inflorescence of the Wildflower. Note—(i) The peduncles, or axis upon which the flowers are placed. +(ii) The pedicels by which the flowers are connected to the peduncle. +(iii) The arrangement of the sessile flowers springing from different parts of the peduncle and thus form a raceme. + +**Exr.t. 151.—Obtain a Plantain and examine it. Note—(i) The peduncles are long and slender, and support the peduncle from view. +(ii) The flowers do not possess stalks, or are sessile on the peduncle. +(iii) The arrangement of the sessile flowers shows that the inflorescence is a spike. + +**Exr.t. 152.—Strip off the flowers from an inflorescence of the Daisy. Note—(i) The common receptacle upon which the flowers are placed. +(ii) The flowers are sessile, as in the spike. +(iii) The flowers are arranged in a raceme. + +**Exr.t. 153.—Compare the simple umbel of the Cowslip or Oxlip with the compound umbel of the Foul's Parsley. Note—(i) In the simple umbel each flower is unbranched, while in the compound umbel of Foul's Parsley each pedicel is branched ; and (ii) both come to the same level. + +**Exr.t. 154.—Obtain a Plantain and examine it. Note—(i) The common receptacle upon which the flowers are placed. +(ii) The flowers are sessile, as in the spike. +(iii) The flowers are arranged in a raceme. + +**Exr.t. 155.—Compare the simple umbel of the Cowslip or Oxlip with the compound umbel of Foul's Parsley. Note—(i) In the simple umbel each flower is unbranched, while in the compound umbel of Foul's Parsley each pedicel is branched ; and (ii) both come to the same level.** + +Fig. 174.—Compound umbel of lowest Cusly. +Fig. 175.—Enlarged view of compound umbel of lowest Cusly. +Fig. 176.—Head of Clover. (Line-both size.) + +170 +BOTANY FOR BEGINNERS +CHAP. + +Other Indefinite Inflorescences.—There are a few more indefinite inflorescences which remain to be considered. +Spadix.—The spadix is a cylindrical spike for the flowers. The peduncle is finely and is continued for a distance at a place where the flowers are inserted. It is enclosed by a large + +A, B, C + +Fig. 123.—A, Aman (two-furth nut), with the spadix of Aman, with the front of spadix cut away. C, Spadix, with the whole of the spadix cut away. c., spadix; F, female flower; M, male flower; s.p., individual male flowers. + +leaf called the spathe, which in the wild form is green, but in a cultivated form is white. Examination will show this. + +Catkin.—The catkin is a crowded spike of inconspicuous sessile male or female flowers. When it consists of male flowers alone, it dries off after flowering. The male flowers of the Oak, + +Ap +-sz +-M +F +C + +171 + +XIII +FLOWER AND INFLORESCENCES +171 + +Hazel, and Sweet Chestnut are arranged in catkins. Both the male and female flowers of the Willow, Poplar, and Birch form catkins. + +Expt. 16a.—In either Apter or May obtain an Aurn and examine it. +Note: +(i) The yellow-green spathus which surrounds the spadix is it longer than the spadix. +(ii) The spadix is greenish-yellow. Notice the inside is, as a rule, full of small florets. +(iii) The spadix, which is thick and fleshy, is seen within and is generally covered by the spathus. +(iv) The female flowers are at the base of the spadix and the male flowers at its top. Surrounding them is a ring of undivided male flowers just close the fertile male flowers. + +Expt. 16b.—Collect a few catkins of Hazel. They are produced in April or May. +(1) The external appearance of the inflorescence. It is pendulous. +(2) Remove a single flower with a pin. Observe each flower is composed of two stamens and one pistil. The stamens are found in each flower. +(3) Observe the arrangement of male flowers. + +Relation between Infinite Inflorescences.—The raceme differs only from a spike in having pedicels which separ- +ate the flowers, so that they make a better show and are more +likely to be noticed than those which grow on a common stalk like a spike. + +The panicle, which is a compound raceme, generally bears only small flowers, and the arrangement of these on the ends +of short branches resembles that of a spike but is more lax. It differs from both the spike and raceme ; from the former in possessing stalks, and from the latter in having these branched. + +The panicle differs from the raceme in that the length of the branches varies according to the number of flowers being brought to the same level. Thus, a more or less flat surface, upon which insects love to alight, is formed. + +In the head the same result is obtained by the flowers being crowded together on a flat receptacle, an arrangement which also makes them very conspicuous. + +Insect-pollination occurs in both spikes and panicles are spikes; the former is a catkin of male flowers, while the latter bears both male and female flowers. The catkins are produced before the leaves, and by their pendulous position aid in the distribution of the pollen by the wind. + +172 +BOTANY FOR BEGINNERS +CHAP. + +Definite Inflorescences.—A definite inflorescence is one where the uppermost flower opens first and the lower ones in + +A diagram of definite inflorescence, A, dichotomous cyme; B, helicoid cyme; C, scapoid cyme. + +regular order, beginning at the top. In such an inflorescence it is possible to say where the flowering will cease. Such inflor- +escences are also called cymes. The apex of the shoot produces a flower, which deve- +lops first, the flowering being continued by the production of sec- +ondary branches. The following are the principal forms of de- +finitive inflorescences: + +**Solitary Flowers.**—In the few cases where the apex of the shoot produces only one flower, the flower is said to be solitary. Example—Tulip. + +The flower may also be produced in the axil of a leaf, when it is said to be solitary and axillary. Example—Pomegranate. + +Weatherbe, gloss., and Ground Ivy. (Fig. 175.) + +**Dichotomous Cymes.**—Cymes are occupied by From beneath this flower new branches are produced, and +the dichotomous cyme the apex of each branch also + +A diagram illustrating a dichotomous cyme. + +An illustration showing a solitarily flowered plant. + +XIII FLOWER AND INFLORESCENCES 173 + +produces a flower. Thus, in a dichotomous cyme each apical growing point eventually produces a flower. Examples--Stitchwort and Sandwort. (Fig. 170.) + +**Scorpioid Cyme.--** When the cyme is developed on one side only of the peduncle, and is in the young state rolled up in a spiral manner, it is called a scorpioid cyme. Example--For-get-me-not. (Fig. 177.) + +**Verticillate Cyme.--** The flowers are produced on opposite sides of the stem, in the axils of leaves, and they stand tier above tier, the inflorescence is called a *verticillaster*. Some botanists call this type of cyme a *verticillate* cyme. In this case, too, the flowers will be seen to grow from the axils of leaves, and only appear to be whorled. Example--Deadnettle. (Fig. 178.) + + +A diagram showing a dichotomous cyme with lateral flowers. + + +Fig. 176.--Dichotomous cyme of the Stitchwort. T, terminal flower; L, lateral flower. + + +A diagram showing a verticillate cyme with flowers in the axils of leaves. + + +Fig. 177.--Verticillate cyme of the Forget-me-not. +XIII + +174 +BOTANY FOR BEGINNERS +CHAP. + +**Glomerule.**—When the flowers belonging to a number of cymes are crowded and rolled together so as to form a head, the inflorescence is called a glomerule. Examples—Nettle, Box, Valerianella. + +A diagram of Forget-me-not. + +Fig. 177.—Diagram of Forget-me-not. + +**Cymose.**—When the flowers are produced in a cyme, and from beneath this the branches are produced. + +EXPL. 163.—Obtain a Dandelion when in flower. Note that the branches are dichotomous, i.e., in a forked manner, and the inflorescence is a dichotomous cyme. + +EXPL. 165.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +**Relation between the Definite Inflorescences.**—The variation in the different kinds of inflorescences depends upon the mode of branching of the shoot. This is shown in the following table: + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + <
Mode of BranchingInflorescence
DichotomousCyme
VerticillateCyme
VerticillateCorymb
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
VerticillateScorpioid Cyme
Verticillate



















































































<
+ +A diagram of Verticillate Inflorescence. + +Fig. cyf.—Verification of the Dandilion. + +EXPL. 164.—Collect the inflorescence of the Sisthitchwort (it flowers from April to August) and examine it. Note that (1) The branches are dichotomous, and from beneath this the branches are produced. + +(2) The inflorescence is verticillate, i.e., in a forked manner, and the inflorescence is a verticillate cyme. + +EXPL. 166.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 167.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 168.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 169.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 170.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 171.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 172.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 173.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 174.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 175.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 176.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 177.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 178.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 179.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 180.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 181.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 182.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 183.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 184.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate. + +EXPL. 185.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +(1) Each pair of leaves produces flowers, those in the lower ones opening first. + +(2) The inflorescence is a verticillate + +EXPL. 186.—Obtain a Dandelion when in flower. Note that each pair of leaves produces two pairs of opposite leaves. + +XIII +FLOWER AND INFLORESCENCES +175 + +differs from the dichotomous cyme in which the lateral buds produce branches on both sides of the apex. In the glomerule the branching brings the flowers to the same level and appears to be continuous. + +Bracts.—The bracts are borne upon the inflorescence (p. 46). They are leaves in the axis of which the flowers are produced. + +A flower with five petals and a central disc. +Fig. 173.—Two views of the common daisy, *Bellis perennis*. A, flower; M, bracts of involucre. +B, flower; M, bracts of involucre. + +There may be one large bract only, which surrounds the central disc as at Arum. (Fig. 173.) In some cases these bracts are brightly coloured. Very small bracts are often found at the base of each pedicel, as in the Hymenocallis, when they are termed bracteoles. + +*Involucres*—When the bracts are arranged around the dome-shaped receptacle as in the Daisy and Dandelion, they form an involucre. (Fig. 173.) The bracts of the involucre may be leafy, scaly, or partly leafy and scaly. They may be imbricated like a fan, or simple. + +The Anemone has an involucre of three bracts, just below the flower. (Fig. 180.) + +A flower with five petals and a central disc. +A B + +M R M + +176 +BOTANY FOR BEGINNERS +CHA:8 + +SUMMARY. +Floral leaves are modified leaves which build up the flowers. They have three parts, viz., (1) the calyx, (2) the corolla, (3) the stamens. + +(1) The calyx, which form the calyx. +(2) The petals, which form the corolla. +(3) The stamens, which are organs of reproduction, is built up of stamens. + +The gymnosperm (gymnos), or female organ of reproduction, is built up of carpel. + +Stamens are a stalk—the filament, and a head—the anther. Pistils are built up of one or more carpels; they consist of ovary, stigma, and style. + +The flower is supposed to be a modified shoot or branch, for the following reasons: +(1) The flowers are produced in the same positions as the buds, viz., at the apex of the main shoot and in the axils of leaves. +(2) The flowers are attached to a stem by a general plant manner. +(3) The floral leaves may be leaf-like. +(4) The flowers are often surrounded by floral leaves and the various kinds of floral leaves are known. + +The flower is a common cultivator. + +An inflorescence is a collection of flowers produced from a common shoot. The common shoots are called peduncles. A peduncle is a stalk on which stalks by which the flowers are attached to it is termed pedicels. There are two kinds of inflorescences, (a) indefinite inflorescence, (b) definite inflorescence. + +Definite inflorescence—The flower opens at the base first and closes at the top. Examples: Tussilago, Coriaria, Cynara, Simple Umel, Compound Umbel, Capitulum, Spadix, Cuckoo. + +Indefinite inflorescence are Solitary, Dichotomous Cyme, Verticillaster, Gomphotheca. + +Bracts are greatly modified leaves in the axis of which the flowers are produced. When these bracts are persistent after the flowers fall off they is called a spathe. An involucre is a collection of bracts which gradually become modified into perianth. + +QUESTIONS ON CHAPTER XIII + +(1) Distinguish between a "flower" and an "inflorescence." Illustrate your answer with examples. +(2) Explain, with examples, the following terms—hearts, stipules, petiole. +(3) What is a flower? What structures compose it? +(4) Explain the differences between definite and indefinite inflorescences, giving examples of each. + +XIII +FLOWER AND INFLORESCENCES + +(5) Give examples of the following kinds of inflorescences, and ex- +plain their relation to each other—spike, raceme, panicle, head, umbel, +(Sp. 30.) +(6) Describe and compare the inflorescences of the Wallflower, +Forsley, and Daisy. (1891.) +(7) By giving suitable examples, the following forms of in- +florescences, and point out the relation which exists between them— +Spikes, Racemes, Panicles. +(8) Fully describe the inflorescence of any three of the following +plants—Carnation (Dianthus), Dandelion (Taraxacum), and the orchid +(Myosotis), Deadnettle (Lamium), Foxglove (Digitalis). (1891.) +(9) What is a bract? What plants possess bracts? +(10) What is an involucre? What plants possess involucres? +(11) Explain how a bracteole differs from a spathe. + +N + +CHAPTER XIV. + +THE TERMS USED IN DESCRIBING THE FLOWER + +Terms.—In describing the structure of a flower it is necessary to use a number of terms or names to define the appearances which the organs of a flower may present. It must be distinctly understood that these terms are not arbitrary, but are used to show how to apply them is of little use. In all cases the flowers themselves should be examined and their peculiarities of structure noted, before attempting to describe them by means of terms. + +The Torus.—The upper portion of the flower stalk upon which the floral leaves are fixed is called the torus or receptacle. It is usually circular, but may be conical, or even flat between the stamens and the pistil into a disc. The disc may be club- cup- or urn-shaped. Upon the shape of the receptacle will depend whether the flower is complete or incomplete. + +Complete and Incomplete Flowers.—If the flower is built up of calyx, corolla, stamens, and pistil, it is said to be complete; if any one or more of these parts are absent the flower is said to be incomplete. + +The Buttercup, Wallflower, and Primrose are examples of complete, and the Aneumon, Hazel, and Oak of incomplete flowers. + +Perfect and Imperfect Flowers.—When the flower possesses both stamens and pistil it is said to be perfect. The Asenathum, Dog's Mercury, and Oak are examples of either the stamens or pistil is absent the flower is said to be imperfect. The Hard, Dog's Mercury, and Oak are examples of imperfect flowers. + +Regular and Irregular Flowers.—When the flower can + +CH. XIV TERMS USED IN DESCRIBING THE FLOWER 179 + +be divided into equal halves in any plane, it is said to be regular or actinomorphic. If the flowers of the Hyacinth and Wallflower are examined they are seen to be regular or actinomorphic, for if a sharp knife is used they can be cut into equal halves in any + +Fig. 183.—Female Flowers of Dog's Mercury. +**Fig. 183.—Actinomorphic flower of the Primrose ; the dotted lines show the planes of division.** + +Fig. 182.—Zygomorphic flower of the Pen ; the dotted lines show the plane of division. + +plane which passes through the centre of the flowers. (Fig. 182) + +The flowers of the Pen and Deadnettle can only be divided into equal halves in one plane. Flowers of this kind are said to be irregular or zygomorphic (Fig. 183). If a flower cannot be + +N 2 + +
+

divided into equal halves in any plane it is said to be axymetrical, as in a few plants which belong to the Pink family.

+

The part of the flower at the top of which it stands is called the anterior part; while the portion which faces the axis of the inflorescence is the posterior part.

+

The plane which passes through the flower in such a way as to divide it into anterior and posterior parts is said to be median.

+

Again, the plane which passes through the middle of the inflorescence is said to be the median plane.

+

Expt. 160.--Take an Exsertum, or Gorse, or Laburnum and examine it.

+

(i) The large petal which revolves round the standard is posterior, but the axis of the inflorescence is anterior, which slightly adheres, and are called the anterior, because they face towards the bracts.

+

(ii) The two petals, one on each side of the standard, are called lateral; i.e., they are lateral, i.e., they are on either side of the standard.

+

(iv) The flower is irregular, or irregularly, because its petals do not revolve round the standard.

+

There is only one plane along which a median plane can divide it into equal halves. This plane passes through the center of the standard and from one side to another.

+

Expt. 167.--If the flower of the Apple or Blackberry can be ob-

+

tained, examine it with a pair of scissors and cut off five sepals and five petals.

+

Can it be divided into equal halves in any plane, therefore it is regular?

+

Shape of Flower.--There are a number of terms which are used in describing the shape of the flower. It is said to be--

+

Conic-shaped, whose petals straighten like the form of a cross, as in the Willow-rose and Cabbage (Fig. 183).

+
+ +xiv TERMS USED IN DESCRIBING THE FLOWER 18i + +2. **Papilionaceous**, when butterfly-shaped as in the Pea and Goose (Fig. 180). + +3. **Spurred**, when a spur is formed either from the corolla or calyx. This spur may be used for storing up honey. Examples—Crocus, and the Tuberose (Fig. 181). + +4. **Tubular**, when a tube is formed as in the florets of the Thistle. (Fig. 185). + +Figs. 179, 180. +Crocus-flower. Papilionaceous flower. +Fig. 181. +Spurred flower. +Fig. 182. +Tubular flower. + +5. **Rotund**, when the tube of the flower is short and the lobes flat and spreading, so that it resembles a wheel. Examples—Potato, and Forget-me-not. (Fig. 189). + +6. **Funnel-shaped**, when it is shaped like an inverted cone, as in the Convolvulus. (Fig. 190). + +Fig. 183. +Rotund flower. +Fig. 184. +Funnel-shaped flower. +Fig. 185. +Ligustrum-flower. +Fig. 186. +Campanula-flower. + +7. **Ligulate**, when strap-shaped, as of the floret of the Dandelion (Fig. 192). + +8. **Campanulate**, when bell-shaped, as in the Harebell and Clustered Bluebell. (Fig. 192). + +182 +BOTANY FOR BEGINNERS +CHAP. + +q.—Personate, when the throat of the flower is marked, as in the Snap-dragon. (Fig. 193.) + +10.—Lobate, when the flower is two-lipped, as in the Dead-nettle (fig. 194). + +Size of Flower.—The flowers may be very small, so that it is necessary to use a hand-lens to make out their different parts, or they may be large and show all their characters. The general rule for a large number to be produced. When large flowers are produced by a plant, only a few are necessary to give an idea of the character of the flower should be given when describing it. For instance the diameter of the flower of the Wallflower is given as +1 + +Style + +Fig. 195. +Personate flower. + +Fig. 196. +Lobate flower. + +Fig. 197.—A longitudinal section of the flower of the Wallflower showing inferior ovary and superior perianth. + +inches ; while the flower of the Fool's Parsley is 4 of an inch in diameter. + +Coloured.—In describing a flower its colour must always be noted. Some flowers are green, others are brightly coloured. The Wallflower is yellow or reddish brown, the Hare-bell is blue, the Honeysuckle white, and the Anemone generally white. If the flower possesses any peculiaries such as markings, hairs, &c., they must be described. + +Perfume.—Those flowers which are visited by insects must be sweet scented, but those which are pollinated by birds have no perfume, but if the flowers open at night they are very sweet scented. The characters of the flowers as to perfume, must be recorded when writing the description of the flower. + +Cohesion and Adhesion.—The term cohesion is used + +xiv TERMS USED IN DESCRIBING THE FLOWER 183 + +to note union between similar members, as sepal to sepal or petal to petal. *Adhesion* is used to note union between dissimilar members, as sepals to petals, stamens to petals, &c. + +Calyx. The calyx is the receptacle of the flower, which is separated from each other, or may grow together by their edges to form a cup. If the sepals are distinct, as in the calyx of the Eucalyptus, they are said to be separate; but if they are united, as in the sepals of the Calceolaria, they are said to be united. If the sepals are united so as to form a cup the calyx is gamosepalous, as in the Decandrate and Primrose (Fig. 162). + +When the calyx is fixed below the pistil it is inferior, as in the Wallflower and Buttercup. (Fig. 163.) If the calyx is above the pistil it is superior, as in the Primrose and Parsley. (Fig. 153.) + +The number of the sepals is noted and the name given when they are five, as in the Primrose and Wallflower ; showing superior corolla and inferior perianth. + +Make in the gamosepalous calyx the number of the sepals can only be four or five. When four are present, they must be made out. If there are five lobes to the calyx it is a five-lobed calyx, as in the Primrose and Teadflax. The number of rows of lobes in a calyx is called its order. There may only be one row, as in the Buttercup, or two, as in the Wallflower. The shape of the sepals or lobes of the calyx is of immense importance in distinguishing plants. Leaves 38-40h and the same terms are used in describing both. The free portion of the calyx may be entire, toothed, or lobed. The + +Fig. 163.—A longitudinal section of the flower of the White Lily ; showing superior corolla and inferior perianth. + +Stigma + +Style + +Druy + +Perianth + +184 BOTANY FOR BEGINNERS CHAP. + +lobes may be shaped like the tips of the leaves, (p. 44), and the same terms are used as in describing leaves. +The colour of the calyx may be hairy or smooth, must be recognised. If the calyx is coloured it is said to be **petaloid**, as in the Christmas Rose and Anemone. In most cases it is green. + +The function of the calyx is to protect the stamens and pistil from injury. In those cases where it is coloured it serves to attract insects. It may persist after those functions are per- +formed, as in the Dandelion (fig. 307) of which hairs which aid in the distribution of the seeds by the action of wind are shed off when the flower opens. The calyx may take part in forming the fruit, as in the Corolla—If the petals are united, as in the Primrose, a gametocarpic corolla is formed. The corolla consists of a number of separated petals, and it is **petaloid**, as in the Buttercup, Wallflower, and Stitchwort. + +For fig. 307.—Poppies of Dandelion. + +It is **hypogynous**, as in the Primrose, because the pistil and from the **thalamus**, as in the Wallflower, Rock Cress, and Poppy, if the petals are shed on the calyx is **perigynous**, as in the Christmas Rose and Apple. +[If the flower has the corolla and stamens hypogynous, it is a **hypogynous flower**; if the corolla and stamens are perigynous, it is a **perigynous flower**.] If both corolla and stamens are inserted on the ovary it is an epigynous flower.] + +The corolla may spring from the top of the ovary, when it is said to be epiygenous, as in the Christmas Rose and Apple. + +The number of lobes of a corolla, the shape of the petals, or the lobes, must be observed and the terms used for the calyx may be employed to describe them. + +Androecium—the whole collection of stamens of a flower constitute the androecium. In describing this union the union + +xiv TERMS USED IN DESCRIBING THE FLOWER 185 + +or cohesion is of importance. When the stamens are distinct or separate they are said to be free, as in the Buttercup and Rock Cress. If there are four stamens and two of them are short and two long, they are ditichous, as in the Deadnettle. + +Figs. 196.—Section of flower to show the stamens. +Figs. 197.—Section of flower to show the stamens. +Figs. 200.—Monadelphous stamens. +Figs. 201.—Didelphous stamens. +and Foxglove. In the Wallflower there are six stamens ; two are short and four long. They are said to be tetradynamous. +If the filaments are united they may be : +Monadelphous, all in one bundle, as in the Laburnum. +Polyadelphous, in two bundles, as in the Penstemon. +Polyadelphous, with several filaments of united filaments, as in the St. John's Wort. +Syngenesious, when the stamens are united by their anthers, as in the Daisy and Dandelion. +The adhesion of the stamens must be described in the following terms: +**Epigynous**, when inserted from beneath the pistil, as in the Buttercup, Wallflower, and Stitchwort. +**Perigynous**, when inserted on the top of the pistil, as in the Pec's Foresay and Hemlock. +**Egypnous**, when united to the corolla, as in the Primrose, Mignonette, and Gomphrena, but the stamens are joined to the pistil, as in the Spotted Orchis. + +Figs. 202.—Polyadelphous stamens. + +i86 +BOTANY FOR BEGINNERS +CHAP. + +**Filament.**—The relative length of the filaments and pistil must be noted. The stamina are long if longer than the pistil, and short if shorter than the pistil. The filament may be hairy, or petiolate. If the filament does not bear an anther the stamina is called a staminode. + +**Anther.**—The anther is a rule two-lobed, these being joined by a rib—the connective. The anther may be united to the filament so that it is free to swing, when it is called versatile. If it is joined to the filament by a stalk, it is said to be sessile. When the filament enters the back of the anther it is forked. If the lobes of the anthers face the pistil they are interne, and when they turn away curvate. + +**Gynoecium.**—The filaments and pistils constitute the carpels of a single flower constitute the gynoecium. The cohesion of the carpels is included in describing a flower. There are three kinds of carpels: + +Monocarpous, when the pistil consists of a single carpel, as in the Paea and Gorse. (Fig. 184.) + +Apoecious, when there are two or more carpels and they are separate or distinct, as in the Buttercup and Strawberry. (Fig. 163.) + +Symplocous, when there are two or more carpels and these are united together, as in the Wallflower, Deadnettle, and Hyacinth. (Fig. 190.) + +The function of the pistil is inferior when it is inserted above the other parts of the flower, as in the Buttercup and Foxglove. If the pistil is inserted below the other parts of the flower it is said to be inferior, as in the Fowl's Parsley and Daffodil. + +**Stigma.**—The stigma is usually flat or convex according to the length of the stamens. It may be hairy, angular, or round. If the style springs from the side of the ovary it is lateral, from the top of the ovary it is terminal. In some plants there will be one style to each carpel of an apocarous pistil. In syncarpous pistils, the styles may be separated along their whole length or along part of their length, or united along their whole length. + +**Stigma.**—The apocarous pistil will, as a rule, have one stigma to each carpel; but in some plants where there are two or more carpels a stigma can be obtained by noting the number of the stigmas. Thus if there are three stigmas—the number of carpels + +A diagram showing different types of gynoeciums. + +xiv TERMS USED IN DESCRIBING THE FLOWER 187 + +in the pistil will be three. The stigmas will, according to the number present, be 3-6d., 5-6d., 4-6d. &c. They may be round, square, feathery, or petaloid. When the style is absent the stigmata are called papillate. + +**Placentation.—The place where an ovule is fixed to the ovary is known as the placenta, and the way in which they are arranged on the ovary is called placentation.** The arrangement of the ovules in the ovary can be determined by cutting across the ovary, and if it is small by using a knife and a pair of scissors. There are several kinds of placentation, which are known as :- Placental Placentation, when the ovules are attached to the wall of the ovary (Fig. P, 20). In such an ovary there is generally one chambered. In Wallflower there are two. (Fig. P, 20.) + +**Axile Placentation,** when the ovary is syncarpous, and the carpels meet in the centre and from this longitudinal axis the ovules grow, as in the Daffodil, Hyacinth and Tulip. The ovary generally possesses as many cells as there are carpels ; the ovules are attached to the axis. (Fig. A, 20.) + +**Basal Placentation,** when the chamber of the ovary contains only a single ovule and this springs from the base, as in the Buttercup. + +**Marginal Placentation,** when in an ovary which is formed from a single carpel the ovules are arranged along the ventral margin of the carpel (Larkspur, Helleborus). + +**Perianth.—When the two outer whorls of the flower are alike in colour and appearance it is called a perianth. The** + + +A: A diagram showing a single carpel with an ovule attached to its ventral margin. +B: A diagram showing a single carpel with an ovule attached to its dorsal margin. +C: A diagram showing a single carpel with an ovule attached to its lateral margin. +D: A diagram showing a single carpel with an ovule attached to its basal margin. +E: A diagram showing a single carpel with an ovule attached to its apical margin. +F: A diagram showing a single carpel with an ovule attached to its median margin. +G: A diagram showing a single carpel with an ovule attached to its lateral margin. +H: A diagram showing a single carpel with an ovule attached to its basal margin. +I: A diagram showing a single carpel with an ovule attached to its apical margin. +J: A diagram showing a single carpel with an ovule attached to its median margin. +K: A diagram showing a single carpel with an ovule attached to its lateral margin. +L: A diagram showing a single carpel with an ovule attached to its basal margin. +M: A diagram showing a single carpel with an ovule attached to its apical margin. +N: A diagram showing a single carpel with an ovule attached to its median margin. +O: A diagram showing a single carpel with an ovule attached to its lateral margin. +P: A diagram showing a single carpel with an ovule attached to its basal margin. +Q: A diagram showing a single carpel with an ovule attached to its apical margin. +R: A diagram showing a single carpel with an ovule attached to its median margin. +S: A diagram showing a single carpel with an ovule attached to its lateral margin. +T: A diagram showing a single carpel with an ovule attached to its basal margin. +U: A diagram showing a single carpel with an ovule attached to its apical margin. +V: A diagram showing a single carpel with an ovule attached to its median margin. +W: A diagram showing a single carpel with an ovule attached to its lateral margin. +X: A diagram showing a single carpel with an ovule attached to its basal margin. +Y: A diagram showing a single carpel with an ovule attached to its apical margin. +Z: A diagram showing a single carpel with an ovule attached to its median margin. +AA: A diagram showing a single carpel with an ovule attached to its lateral margin. +BB: A diagram showing a single carpel with an ovule attached to its basal margin. +CC: A diagram showing a single carpel with an ovule attached to its apical margin. +DD: A diagram showing a single carpel with an ovule attached to its median margin. +EE: A diagram showing a single carpel with an ovule attached to its lateral margin. +FF: A diagram showing a single carpel with an ovule attached to its basal margin. +GG: A diagram showing a single carpel with an ovule attached to its apical margin. +HH: A diagram showing a single carpel with an ovule attached to its median margin. +II: A diagram showing a single carpel with an ovule attached to its lateral margin. +JJ: A diagram showing a single carpel with an ovule attached to its basal margin. +KK: A diagram showing a single carpel with an ovule attached to its apical margin. +LL: A diagram showing a single carpel with an ovule attached to its median margin. +MM: A diagram showing a single carpel with an ovule attached to its lateral margin. +NN: A diagram showing a single carpel with an ovule attached to its basal margin. +OO: A diagram showing a single carpel with an ovule attached to its apical margin. +PP: A diagram showing a single carpel with an ovule attached to its median margin. +QQ: A diagram showing a single carpel with an ovule attached to its lateral margin. +RR: A diagram showing a single carpel with an ovule attached to its basal margin. +SS: A diagram showing a single carpel with an ovule attached to its apical margin. +TT: A diagram showing a single carpel with an ovule attached to its median margin. +UU: A diagram showing a single carpel with an ovule attached to its lateral margin. +VV: A diagram showing a single carpel with an ovule attached to its basal margin. +WW: A diagram showing a single carpel with an ovule attached to its apical margin. +XX: A diagram showing a single carpel with an ovule attached to its median margin. +YY: A diagram showing a single carpel with an ovule attached to its lateral margin. +ZZ: A diagram showing a single carpel with an ovule attached to its basal margin. +AAAAA: An illustration of various types of placentation in flowers. Each letter represents different types of placentation, such as axile, basal, marginal, etc., and shows how the ovaries are divided into chambers and how the seeds are distributed within them. For example, 'A' shows axile placentation where seeds are distributed along the central axis of the flower; 'B' shows marginal placentation where seeds are distributed along the margins of the petals; 'C' shows basal placentation where seeds are distributed at the base of the flower; 'D' shows perianth placentation where seeds are distributed equally among all parts of the flower. The illustrations also show how different types of flowers have different numbers of petals and sepals, and how these factors affect their placentation patterns. For example, 'E' shows that some flowers have more than one chamber in their ovaries while others have only one; 'F' shows that some flowers have more than one whorl of petals while others have only one; 'G' shows that some flowers have more than one whorl of sepals while others have only one; 'H' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'I' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'J' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'K' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'L' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'M' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'N' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'O' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'P' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'Q' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'R' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'S' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'T' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'U' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'V' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'W' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'X' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'Y' shows that some flowers have more than one whorl of petals and sepals while others have only one; 'Z' shows that some flowers have more than one whorl of petals and sepals while others have only one; AAAAABBBCCCDDDDEEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIIJJKJKKKLLLLLLMMMNNOONNOOPPOPPPPQQQQQRRRSSSTTTTUUUVVWWWWWXXXYYYZZZZZAAAAAAAABBBBBCCCCCDDDDEEEEFFFFGGGGGHHHHIIIII + +i88 +BOTANY FOR BEGINNERS +CHAIF. + +floral-leaves are then called perianth-leaves. In most monocotyledonous plants it is usual to speak of the two whorls--calyx and corolla--as one unit, the Hyacinth, Tulip, etc., being thus treated. If the leaves of the flower are petiolate, it is **pétalifolius**, and if united **zygophyllus**. If the stamens are united to the leaves of the perianth, they are **epiphyllicus**. When the perianth is coloured like petals it is said to be petaloid. + +Floral Formulae.--The number and arrangement of the floral leaves in a flower is expressed by a formula. The floral formulae the whorls are represented by letters, and the number of leaves in the whorl by corresponding figures, or, if the number is one, by a single figure. The position of each leaf is represented in a whorl by -- coming between the corresponding figures. The cohesion or union of the leaves in a whorl is indicated by ( ), the stalks of ( ) and superior organs are shown by - below the common base of ( ), and when inferior by a line above the figure. + +If the flower is symmetrical or irregular the sign ( ) is added. If the flower is regular the whorls are perianth, an = calyx, c = corolla, al = androecium, g = gynaeceum. The following are examples of floral formulae. + +Insect-pollinated flowers. +Apple blossom: [K5C3C5A3]G(3). +Foxglove: [K3(C5)A3]G(3). + +Primrose: [K5(C5)A3]G(3). +Tulip: [P3 + A3 + S3]G(3). + +Floral Diagrams.--The parts which of the flower consists can be shown on a diagram by drawing a ring forming a ground plan or map of the flower. To gain an idea of the arrangement of the whorls in a flower, cut across a flower bud so as to separate its parts. Then examine how many leaves appear on the surface of the flower; in a flower with three whorls, three leaves will be seen in their proper position. The sepals will form the outer circle, and will be followed by petals, stamens and stamens and petals come. To construct a floral diagram make the number of rings required with a pair of compasses, and on the rings show the position of the floral leaves. Fig. 204 is an example of a floral diagram. + +xiv TERMS USED IN DESCRIBING THE FLOWER 189 + +**How to describe a Flower.**—In describing a flower the following plan should be followed, taking the organs in the order shown. + +**Flower.**—(a) Whether complete or incomplete. +(b) Whether achinomorphic or zygomorphic. +(c) Shape. +(d) Diameter, colour, perfume. + +**Calyx.**—(a) Whether polysepalous or gamosepalous. +(b) Number of sepals or lobes of calyx. +(c) Whether free, imbricate, or valvate. +(d) Shape of calyx or sepals, markings, colour, smooth or corrugated. +(e) Corolla.——(a) Whether polysepalous or gamosepalous. +(f) Number of petals of corolla. +(g) Number of stamens. +(h) Whether superior, hypogynous, perigynous, or epigynous. +(i) Shape of petals or lobes of corolla. + +**Androecium.**—(a) Whether free, monadelphous, diadelphous, or polyadelphous. +(b) Number of stamens or indefinite. +(c) Whether hypogynous, perigynous, epigynous, epipetalous, or gynandrous. +(d) Size and length of filaments. +(e) Whether anther two-lobed, and how fixed to filament, introrse or extrorse. + +**Gynaeceum.**—(a) Whether monocarpous, apocarpous, or syncarpous. +(b) Number of carpels. +(c) Whether inferior or superior. +(d) Whether sessile or short. +(e) Whether stigmas terminal, 2-6d, 3-6d, 4-6d, &c. +(f) Whether ovary one, two, three, or more celled. + +**Ovary.**—(a) How many? +(b) Fertilenation—axile, parietal, free-central, marginal, or basal. + +Then represent the parts and arrangement of the flowers in floral formulae and floral diagram. + +190 +BOTANY FOR BEGINNERS +CHAP. + +ExrT. 168.—Examine a flower of the Anemone and describe it, taking its organs in the following order— + +(i) Flower—Complete, zygomorphic, one in diameter, white, faintly scented. +(ii) Corolla—A—Petals—Free, indefinite, hypogynous, filaments long, another two-lobed, basifixed, extrorse. +(iii) Gynostemium—Monocarpous, anther capsules numerous, superior, styles short, stigma terminal. +(iv) Filial formula—K=3+2+Ca, A=Ca, G=Ca. + +ExrT. 169.—Examine a Wallflower and describe it, taking its organs in the following order— + +(i) Flower—Complete, zygomorphic, crassifolium, 1½ inches in diameter, reddish-brown, sweet scented. +(ii) Corolla—A—Petals—Free in two series, inferior, inner scales sacrate (p. 152) lanceolate, hairy. +(iii) Gynostemium—Monocarpous, four, hypogynous, petals clawed, limb oblongate, claw linear. +(iv) Androecium—Four stamens series, interstitialis, hypogynous, monospermous, filaments thick, anthers two-lobed, dorsal, +fixed, intercalary. +(v) Filial formula—K=3+2+Ca, A=Ca. + +Fig. 204.—Floral diagram of Wallflower. + +ExrT. 170.—Examine the flower of the Dandelion (Taraxacum or Borzoi), and describe it, taking its organs in the following order— + +(i) Flower—Complete, zygomorphic, one in diameter, papilionaceous, yellow. +(ii) Corolla—Petals—Papilionaceous, inferior, green. +(iii) Corolla—Polyvalent leaf (consisting of standard, wings and keel), petaloid. +(iv) Androecium—Monocarpous, ten perigynous, anthers two-lobed, +ventral. +(v) Gynostemium—Monocarpous, superior, style long, stigma terminal. +(vi) Gynaeceum—Monocarpous. +(vii) Filial formula—K=3+2+Ca (2+3), A=Ca (2), G=Ca. + +ExrT. 171.—Examine the flower of the Dandelion and describe it, +taking its organs in the same order as before. + +xiv TERMS USED IN DESCRIBING THE FLOWER 191 + +Expt. 17.--Examine the flower of the Daffodil and describe it, taking its organs in the same order as above. + +SUMMARY. + +Terms used to describe the shape and arrangement of the organs of flowers. + +The *tora* is the upper part of the flower stem upon which the floral leaves stand. The *corolla* is a complete flower in one which only corolla, stamens and pistil are present. An *incomplete flower* is one where one or more of the floral whorls are absent. + +An *perfect flower* will contain stamens and pistil. + +An *imperfect flower* will only contain stamens or pistil. + +The *petiole* is that part of the flower stem which is divided into equal halves in any plane. + +The *petiole* of a flower can only be divided into equal halves in one plane. + +The posterior parts of the flower face the base in the axis of which the flower stands. The posterior parts of the flower face the axis of which the flower stands. + +Shapes of flowers. The following list gives the principal shapes of the flowers: + +The *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*, *campanulate*. The coleus of the stamen may be monadelphous, diadelphous, polyadelphous, syngenesious, anisogamous, heterogamous, heterostylic, epigynous, hypogamous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous, perigynous. The coleus of the stamen may be monadelphous, diadelphous, polyadelphous, syngenesious, anisogamous, heterogamous, heterostylic, epigynous, hypogamous, perigynous, perigynous, perigynous, perigynous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be monadelphous. The coleus of the stamen may be mon adel phorous. + +192 +BOTANY FOR BEGINNERS +CH. XIV + +The floral diagram is a graphic way of representing the flower in ground plan. + +QUESTIONS ON CHAPTER XIV. +(1) Explain the term "complete." What is its shape in the Daisy and the Buttercup? +(2) Define the terms "complete" and "perfect." Mention flowers which are complete and perfect. +(3) What do you understand by hypogynous, perigynous and epigynous flowers? Give two examples of each. (506) +(4) Describe the flowers of the following: the Cruciferae (Christmas Rose), Anemone, and Ramicncha (Buttercup). (508) +(5) Discuss the meaning of the following: corolla, calyx, stamens, pistil, ovary, style, stigma, ovule, ovary-axile, axile, and parietal placentation. (509) +(6) Explain the meaning of the following terms-marginal, axile, and parietal placentation. (509) +(7) Explain the meaning of the following terms applied to stamens-diadelphous, tetradynamous, diadynamous, syn- genicous, epipetalous. (509) +(8) Describe the flowers of the Narcissus and the Hyacinth. (509) +(9) Describe three examples, the papilionaceous, the labiate, and the petalate types of corolla. (509) +(10) What is meant by "zygomorphic symmetry"? Give examples. + +CHAPTER XV + +THE DEVELOPMENT AND MORPHOLOGY OF THE FLOWER + +The Development of the Flower.—The young flower buds appear on the stem as rounded outgrowths, and if a series of buds be examined at different stages of their development through them, the order of development of the floral whorls can be ascertained. +If a series of flower buds of different ages is examined from the influence of the Wallflower, the very young bud will be seen to consist of three whorls, the outer one being the anterior one, then the two lateral ones are developed, and last of all the posterior one. In a little older bud the corolla will be seen to have been formed, and the stamens will be appearing and alternating with it. All four petals appear at once. In a bud a little older still the stamens will be seen inside the corolla. The order of the appearance of the stamens is as follows :- +1. The anterior pair of long stamens appear first. +2. The posterior pair next. +3. The posterior pair of long stamens last. + +The pistil is the last floral organ to appear ; the two carpels are arranged together, and can be seen as small projections in the centre of the bud. + +The order of the development of the floral whorls can be far better made out in those flowers which are closely associated in large numbers, such as those of the Wallflower (fig. 168) and the Daisies (p. 168). This is, in the young inflorescence of the Daisy or the Sunflower, nearly all the stages of development can be seen in a single section. If a young capitulum of this Daisy is examined with a hand lens, the youngest flowers can be seen + +O + +194 +BOTANY FOR BEGINNERS +CHAP. + +near the centre, and the oldest towards the edge. From the centre to the edge all stages in the development of the floral organs can be seen out. If a section is cut through the flower, the stamens will be seen at first, then the pistil, and then mounted in glycerine and examined with a high power—the central flowers will show the corolla appearing as if it were a single flower—then the petals will appear, and finally the corolla, five projections will be seen—these are the stamens. In a still older flower the centre of the stamens will be filled in with two or three pistils. + +Thus, in the Daisy the corolla appears first, then the stamens, and last of all the pistil. In the Sunflower the corolla and stamens appear together, but the pistil comes later than all the piths. In the large majority of plants the appearance of the floral whole is the same as in the Wallflower, but as few exceptions are exceptions. + +**Expt. 173.—To see how the Wallflower cut off the young buds from the axis and lay them in regular order, placing the cleft at one end and the younged at the other end. With a sharp knife or razor blade cut off a bud from a young plant of Wallflower. Examine with a hand-lens. Note—(i) The bud consists of a calyx, petals, stamens and pistil coiled up inside the calyx, the parts being very distinct. (ii) The calyx is two-celled, and within each ovary can be seen. (iii) From the outside towards the parts are less distinct. (iv) In the younger growing part is the least distinct, then stamens and finally pistil is the last to appear. (v) This shows that the calyx is developed first and then the pistil last. + +**Expt. 174.—Collect a number of inflorescences of the Daisy or Daisies, and examine them under a hand-lens. Note—(i) The shape of inflorescence. It forms a cone which is irregular in shape. (ii) The shape of inflorescence. It shows that it is not cylindrical. (iii) The largest and oldest flowers are near the edge of the inflorescence, while those which are just opening are near its centre. (iv) This shows that the growing point cuts off leaves from the outer part of the cones first and from near its centre last. + +The **Structure of Petunia** and **Sopala**.—The general structure resemble that of leaves in structure and appearance. They are covered with an epidermis, which contains + +stomata, and between the upper and lower epidermis comes the mesophyll, which is penetrated and strengthened with vascular strand. + +The Texture of the Sepals.--The texture of sepals varies con- +siderably. They may be delicate, firm, membranous, or scaly. The duration of the sepals will depend upon their texture. They may be deciduous, that is, they fall off at the end of the season to be +caducous; if they last until the seeds begin to ripen and then +fall off, they are diciduous; and when they remain until the seeds are +ripe, they are perennials. The texture of the sepals is fre- +quently proved by hairs for protection. + +Functions of the Sepals.--When the sepals are green they +perform the same functions as foliage leaves. They also serve +to protect the flowers from heat and cold. If these petiolate +they may serve to attract insects, as in the Anemone and Lily. + +The Structure and Functions of the Petals.--The +petals and petaloid sepals are covered with a delicate epidermis. +Within the epidermis come one or more layers of spongy paren- +chyma cells, which are separated by thin intercellular strands, +which, as in leafy leaves, gives it a veined appearance. + +The Texture of the Petals.--The texture of the petals is usually smooth or glabrous (p. 29), but in some cases, such as +the seeds ripen. The surface of the corolla may be smooth or +glabrous (p. 29), or present certain hair structures or hair-like +epidermal projections. + +The Colour of Petals and Sepals.--When the sepals and (less often) the petals are green, the colour is due to chlorophyll. If they become yellowish or brownish, this colour being due either to coloured sap or to chromoplasts (p. 18). In +few cases the colouring is due to both. + +In all flowers there is a definite colour, markings, shape, +and perfume of the corolla all are designed to attract insects, +so as to ensure the distribution of the pollen (p. 18). The +petals may be modified to form cup-shaped cups (pistil) of +the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. Petals may be modified to form cup-shaped cups (pistil) of the flower from injury. + +EXTRA.-Put a drawer full of Genusium strip off a petal, and with a sharp knife pull away its surface tissue: Mount the petal in water + +xv +THE DEVELOPMENT OF THE FLOWER 195 + +196 +BOTANY FOR BEGINNERS +CHA.P. + +with the torn surface below, and examine under a low power. +Note—(i) The conical-shaped outline of the cells. +(ii) The cells contain coloured cell-sap. There are no chromatophores present. + +Expt. 176.—Cut transverse sections through a scalpel of the Wall-flower, mount the tintint in water, and examine with the high power. +Note—(i) The epidermis on both the upper and lower surfaces. +(ii) The stomata between the upper and lower epidermis, it contains vascular bundles. + +Expt. 177.—Harvest a few petals of the Wallflower in a coloful, and cut transverse sections through them, and examine in glycerine. +Examine under the low power. Note—(i) The outer epidermis is thin, and shows the characteristic appearance to the petals because they reflect the light. +(ii) The vascular bundles are slender, but consist of xylom and phloem. +(iii) The mesophyll is built up of parenchyma cells. +(iv) The epidermis contains no stomata. + +Expt. 178.—Examine with the hand-lens the base of a single petal of the Wallflower. +(i) The pocket-like nectary which secretes honey. +Note—It is very thin, and can be seen only with a low power. Examine it with a low power and reflected light. Note—(ii) The nectary has a distinct cellularised appearance. +(iii) The epidermis, which consists of small but regularly arranged cells. +(iv) The colouring matter has nearly all disappeared. + +The Essential Floral Organs.—The androecium and gynaeccium form the essential floral organs. They are called the essential organs of the flower, because without them no plants can be produced. In some plants these organs are combined into one, while in the formation of seeds, since many plants which have only stamens and pistil produce seeds. The calyx and corolla do, however, play an important part in protecting the flower from loss of heat as well as from dew and rain; they also by their colour, perfume, and shape attract insects to the flower. + +The Sepals (or Calyx).—The sepals of a flower consists of modified leaves, which bear very little resemblance to foliage leaves. Each stamen is, as a rule, filiform in shape, and consists of a filament or stalk bearing an anther at the apex. They have no vegetative function to perform, but are + +A diagram showing the structure of a flower. + +XV THE DEVELOPMENT OF THE FLOWER 197 + +modified for special work—shot of producing pollen. The fila- +ment represents the petiole of the leaf-olate, and it is traversed by one or more vascular bundles, which is surrounded with endodermis. The vascular cylinder is surrounded by paren- +chyma-cells, which are the epidermis of the filament. These cells are no stomata in the epidermis of the filament. + +The anther represents the blade of the foliage-leaf folded to form two lobes, which are united at the base of the anther, and dividing into two lobes is a midrib—the connective. In the centre of the connective runs a vascular bundle, continuous with that of the filament, and bringing nutritive matter to the anther. The walls of the mature anther, as seen in section, consist of the follow- +ing parts— + +1. The epidermis, the outer walls of which have a well-developed cuticle, and contain a few +stomata. +2. The fibrous layer, +consisting of several layers of cells, which +form a stratified appearance, due to the thickening of the walls. +3. The tapetum layer, sometimes represented by nearly dis- +organised cells, for it is used for the nutrition of the pollen grains. The young anther contains four pollen sacs, but the mature anther contains only two. Each pollen sac is formed in each lobe of the anther uniting just before it becomes ripe. The pollen sacs contain pollen. Each pollen grain is a male reproductive cell. + +The Development of the Stamens.—The first part of the stamens to appear is the anther, and this is formed by the division of a meristem situated on its inner side. These +cells—are, because of their position, called **epidermal cells**; they form what is called the archesporium or meristem layer, from which the anther and pollen grains are formed. The cells of the archesporium divide at four points in the young anther, which + +198 +BOTANY FOR BEGINNERS +CHAP. +correspond to the four pollen sacs. The cells formed by their division give rise to: +1—The cells of the floret layer. +2—The cells of the tapetum layer. +3—the protoplasts of the cells, formed from the inner cells. +4—the epidermis of the anther, formed from the cells above the hypodermic layer. +The first two, or the last portion of the stamen, to be produced; as a rule, it is not fully developed until just before the pollen is ripe. + +The Development of Pollen.—Diagram illustrating the developement of pollen in a dicotyledonous anther. +Each mother-cell divides into four pollen grains in the following manner. The nucleus divides (p. 80) into two, and each half again divides into two, so that there are eight nuclei in each mother-cell. The protoplasm becomes rounded off so as to form separate masses round each nucleus. (Fig. 20.) A new cell wall is produced round each nucleus from the outside, thus separating the nuclei from one another, and they are enclosed. Each cell after ripening forms a pollen grain. The pollen grains are set at liberty by the breaking down of the wall of the mother-cell. Thus, the formation of pollen is one case for all dicotyledonous plants. + +*Monocotyledons—in monocotyledonous plants the formation of pollen is different from what has just been described. The mother-cell of the mother-cell divides into two parts, and between these parts a cell wall is formed which extends right across the cell. Each nucleus again divides and new cell walls are formed between them. Thus, out of the mother-cell four daughter-cells + +Fm. et. al.—Diagram illustrating the development of pollen in a dicotyledonous anther. + + + + + + + + + +
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+ +A diagram illustrating the development of pollen in a dicotyledonous anther. + +XV THE DEVELOPMENT OF THE FLOWER 199 + +are formed. The principal difference, then, is the division by a wall of the cell into two after the division of the nucleus. (Fig. +no.) The pollen grains of dicotyledonous plants are formed by the division of a single cell, while those of monocots by a method which comes between this and vegetative division. (p. 80.) + +The Structure of a Pollen Grain.—The pollen grain is at first surrounded by a very thin cell-wall which with age in- +creases in thickness. The outer layer becomes cuticularised and forms the exine; the inner layer consists of collenchyma and + + +A diagram illustrating the deve- +lopment of pollen in a monocoty- +ledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- +velopment of pollen in a mono- +cotyledonous plant. + + + +A diagram illustrating the de- + +terior. The shape of the grain varies in different plants, but usually it is oblong, flat, or oval, or ridges or be perfectly smooth. Most pollen grains have thin walls +in their exine and out of one or these places they are filled with ground matter. + +The interior of the grain is filled with granular protoplasm, for two nuclei may with great difficulty be made out. The smaller one is situated near to one pole, and is called +the nutritive nucleus. When the pollen grain is placed under suit- able conditions (p. 123) germination takes place, and the intine breaks through the exine to form a long tube called the pollen tube. This tube grows down into and around each ovule. + +Expt. 79.—Cut a transverse section from the flower of any well-developed stamen. Mount it on water and examine, first with a high power. Note— + +(i) The exine and intine layers. + +(ii) A few rows of parenchyma within the epidermis which represent them. + +(iii) One or more vacuolar bundles in the centre of the section ; these are continuous with those of the stem, and bring nutritive materials to both anther and pollen grains. + +199 + +200 +BOTANY FOR BEGINNERS +CHAP. + +Expt. 180.—Cut transverse sections of the young flower bud of the Wallflower. Mount the thinnest in water and examine with a low power. Note the structure of the cells. + +Note. +(i) A single layer of cells, the epidermis, the outer walls of which possess a well-developed cuticle. +(ii) The mesophyll, which is several layers of cells in thickness and appears striated. +(iii) The innermost layer, which is represented by a layer of cells in all stages of disintegration. +(iv) The pollen grains. Some are in the pollen sacs, others in the water. + +Expt. 181.—Transverse sections of a ripe anther of the Wallflower should be made for comparison. To do this it is necessary to immerse in alcohol for a few days. Select the thinnest and mount in glycerine. +Note. +(i) The layers are the same, but better developed. +(ii) The mesophyll is very thin. +(iii) The pollen grains are ripe. +(iv) The anther is very thick-walled and hard. Note— +(iii) The four places in the wall through which the intine grows into form the pores. +(v) The nucellus, the nutritive, is the vegetative one, and the two smaller ones are the generative. These will seem with difficulty. + +Expt. 182.—Immerse in water and examine the pollen grains of the following flowers as they appear—Rock-Cress, Sundew, Hyacinth, Apple, Dandelion, etc., to see how they differ. + +Note. +(i) Their shape and external markings. +(ii) The three places in their walls. +(iii) The three pores. + +Expt. 183.—Cut a piece of cardboard the size of a microscopic slip, and out of the centre remove a circular piece the size of a cover-glass. On the surface of this place a drop of a 5% solution of sugar in water and dry; place a drop of a 5% per cent. solution of sugar in the cell of a living pollen grain (see Expt. 179). Cover with another piece of cardboard and cover with a cover-glass. Incinerate at 100° C. for half an hour. Cool and open up carefully. Dump the cardboard and put in a dark warm place for a few hours. + +Note. +(iii) Many of the grains have sent out pollen tubes filled with granular protoplasm. +(iv) One or more nuclei may be detected in the pollen tube. + +How the Pollen is liberated from the Anther + +When the anther is ripe, the pollen sacs open as soon as the pollen grains at liberty. The anther lobes may open by one split + +THE DEVELOPMENT OF THE FLOWER 201 + +marking the line of junction between two pollen sacs, when the opening is called longitudinal deliquescence. In other cases the anther opens by small pores, as in the Heath and Potato, when, after the pollen has been shed, the anther remains open by small doors or valves when the deliquescence is reticular. + +The Structure of the Gymnoecium.—The gymnoecium con- +sists of a single ovary, which is usually more developed than the stamens from the ordinary folia leaf type. The structure of the carpels as these modified leaves are called, can be studied by examining the flowers cut and examined by the microscope. Each carpel forms to consist of the following parts: + +1.—Lower or upper epidermis. +2.—Several layers of mesophyll. +3.—A number of vascular strands which penetrate the mesophyll, and bring nutritive material to the carpel and its ovule. + +The gymnoecium may consist of a single carpel, as in the Pea, or of several carpellae, as in the Poppy and Lily. In every case the ovary is formed by a single layer of cells forming a cavity—the ovariety. In the ovary the ovules are developed, and they receive the materials necessary for their further growth from the ovary. + +The Structure of an Ovule.—An ovule consists of the following parts: + +1.—The integument or stalk by which it is attached to the placenta or swelling on the wall of the ovary (p. ro). +2.—The integuments or coverings of the ovule, which are separated from each other by a small opening through the integuments, the micropyle (p. ro). +3.—The nucellus, an oval mass of tissue within the integu- +ments. + +4.—The embryo-sac embedded in the nucellus. + +The Embryo-Sac.—The embryo-sac is a large oval cell which contains one or more egg cells. These are situated in the centre of the sac (p. 1). The egg-apparatus, which consists of three cells at the micropyle end of the embryo-sac. One of these cells is the egg-cell, the other two are either two polar nuclei or two synergids, and direct the pollen tube to the oosphere (p. iii). + +xv + +202 +BOTANY FOR BEGINNERS +CHAIF + +antipodal cells, which consist of three cells which are placed at the posterior end of the embryo sac. In many cases these dissepiment break down and form a protuberance. (iv) The **endosperm** or **protoplast**, in which the above structures are em- +bedded. (v) The **ovule**, which is filled with cell-sap. + +The funiculus unites the ovule to the wall of the ovary and con- +tains yolk-like material. It is necessary that this should be present for the development of the ovule and embryo or young plant. +In a few plants the integuments may not be developed. +A most important function of the integuments is the enclosure with its cells. + +Expt. 184.—Cut transverse sections through the open flower of the +Marsh Marigold (Caltha). With the section from the base of the +glass-plate. Mount a section containing ovules in alrite glycerine. +Examine under high power. +(i) The ovules connected to the carpel by short stalks—the funicles. +(ii) The ovules free from the carpel—free ovules. +Examine the embryo-sac under a high power. Note— +(iii) The egg apparatus consisting of two polar bodies and one spermatozoon. +(iv) The cells at the cell at the far end of the embryo-sac from the microspore. +(vi) The embryo-sac nucleus. + +**The Development of the Gynecium**.—The gynecium is +the last part of the flower to appear, and it always occupies +the apex of the floral axis. The carpels may be separate as they +developed from lateral outgrowths of the epidermis (as in an apocarpous gynecium). (p. 180.) The none of tissue just below the carpels begins to develop and carry up the carpels with it. This tissue forms a cup which forms the ovary. Ridges appear on the wall of the ovary. These are the placenta, +from which the ovules will be developed. + +The Placentae.—These are formed as outgrowths of the placentae. Each ovule at first consists of two layers of cells belonging to the epidermis of the wall of the ovary, and to a deeper layer just below it. One cell is larger than its neighbours, and this becomes a nucellus. Two layers +are formed. The integuments and mesocarp are formed from +the cells at the base of the projection. The funicle is also formed +from the cells at the base of the ovule and dies it to the +placenta. + +XV THE DEVELOPMENT OF THE FLOWER + +The large cell which we may call the embryo-sac continues to grow, and its nucleus—that is, it must be remembered the prim- +ary embryo-sac nucleus—divides and the two daughter nuclei migrate towards each other. They do this again. +There are thus two at each end of the sac. They again divide, so that there are eight nuclei in the embryo-sac, four near each end. The protoplasm now forms around three of these nuclei, forming the egg-apparatus, and those at the opposite end the antipodal cells. One nucleus from each end passes towards the middle of the ovule. These also form the secondary embryo-sac +nucleus. + +**Kinds of Ovules:** There are two common kinds of ovules, +and the kinds which they receive depend on their relative posi- +tions of the funiculus and body of ovule. These are explained by the figures given. They are as follows: + +1. The ovule is *Orthotropous* (orthopous) when the funiculus +and the axis of the ovule form a continuous line (Fig. 309, A). + +A diagram showing different types of ovules: A. orthotropous; B. anatropous; C. campylothropous. +Fig. 309.—Diagrams of Ovules. +A. orthotropous; B. anatropous; C. campylothropous. + +The nucellus is then straight, and the micropyte is at the greatest possible distance from the funiculus. + +2. The ovule is *Anatropous* when the funiculus curves sharply, so that its side lies by side with the body of the ovule. (Fig. 309, B.) + +3. The ovule is *Campylothropous* when it is itself +curved so that the micropyte and the chalaza, or basal portion of the ovule, do not lie in the same straight line. (Fig. 309, C.) + +384 +BOTANY FOR BEGINNERS +CHAP. + +SUMMARY. +The floral whorls are developed in the following order— + +The calyx—the anterior sepals appear first, next the lateral, and finally the posterior pair. + +The corolla—All the petals appear together. + +The stamens—The anthers appear first, next the lateral pair, and finally the posterior pair. + +The pistil—The ovary appears last. + +The sepals resemble bundle leaves in structure and appearance. They protect the essential organs from injury, and if petaloid may attract insects. + +The petals differ from bundle leaves in colour and texture. Their principal function is to attract insects by their colour and perfume, and to protect insects. + +The anther is a modified leaf, consisting of antheridium and gynoecium. These are essential for the production of seeds. The antheridium produces pollen grains which are carried by wind or animals to the gynoecium where they germinate and develop into seeds. + +The structure of the antheridium—it consists of modified leaves, bearing on their inner surface a number of pollen sacs. The function is to produce pollen and liberate it. The filament of an anther represents the petiole of a leaf-stalk and the anther lobes the blade. + +The anther consists of the following layers of cells— + +(a) The epidermis—cylindrical or conical bundle; + +(b) the tapetum layer, which generally disappears during the development of the pollen grain; + +(c) the generative cell; + +(d) the nutritive cell. + +The development of palms takes place in the pollen sacs. The mature pollen cells divide up to form four daughter cells—the pollen grain. + +This division takes place in the following way— + +(a) The two nuclei of each pollen grain divide into two each; (c) the protoplast becomes rounded off to form four cells round the nucleus; (d) these four cells become separated; (e) and the daughter cells are set at liberty as pollen grains. + +The pollen grain is a very delicate body, of which part is cuticularised to form the exine; the intine, or intexine, is very delicate and contains a large amount of water. + +(a) A large nucleus—the vegetative one; (b) a small nucleus—the generative one. There are enclosed in each pollen grain two nuclei. + +The anther is usually opened by longitudinal slits, when the delicance is longitudinal; (b) by pores, when the delicance is transverse; (b) by valves, when it is transverse. + +The gynoecium is built up of carpels. Each carpel is a modified leaf. + +The parts present in an ovule are— + +(a) The funiculus or stalk; (b) the integuments or coverings of the ovule; (c) the mouth of which enbryo-sac is embedded. + +**XV THE DEVELOPMENT OF THE FLOWER** + +In the embryo-sac the parts present are— +(a) Egg apparatus—syngenta, oosphere; (b) antipodal cells; (c) em- +bryogeny. +The first part of the syngenta to be developed is the stigma. This is +carried out by the growth of a protoderm which forms the epidermis of the last +part of the ovary and of the carpel or carpels forming the ovary. +The kinds of ovules are as follows— +(i) The orthotropous; (ii) the anatropous; (iii) the campyloptorous. + +**QUESTIONS ON CHAPTER XV.** + +(1) State what you know about the development of (a) the calyx, (b) the corolla, (c) the stamens, and (d) the pistil, in any flowers of your own selection. + +(2) What is the structure of (a) the calyx, and (b) the corolla of any flower? + +(3) Describe the structure of an anther of a pollen grain. (1900.) + +(4) Describe the structure of a pollen grain and its function. (1895.) + +(5) How many pollen grains set at liberty? Give examples. + +(6) Describe the contents of the embryo sac at the time when fertil- +ization takes place. (1895.) + +(7) Give a description of the successive stages in the development of +the embryo-sac. + +(8) Explain the use of the stigma, and describe the structure of the +anther of any flower you may select. + +(9) Name two organs which are formed from each of each, the anatropous, the ortho- +tropous, and the campyloptorous ovule. (1893.) + +(10) Of what parts does an ovule consist? Where are ovules found, +and how are they held in position? + +(11) Explain and diagram the following terms—anatropous, tapetum, syngenta, antipodal cells. + +A diagram showing the structure of a flower, including petals, sepals, stamens, and pistil. + +CHAPTER XVI + +POLLINATION AND FERTILISATION + +Flowering Plants.—There is one feature in which all flowering plants differ from all other flowering plants—that is, the production of seeds. Seeds are often called "fruit" as seed plants in contradistinction to seedless plants. If certain conditions are fulfilled, the ovules become changed into seeds. There is no other way by which the seeds can be produced than through changes in the ovaries which convert them into seeds. The ovules of to-day become the seeds of to-morrow, and the seeds of to-morrow become the seeds of to-morrow. + +The conditions which are necessary for the conversion of an ovule into a seed are as follows: + +(1) The pollen grain must find its way on to the stigma of the pistil. This transference of the pollen from the anthercium to the gynaeccium is called pollination. + +(2) The pollen grain must germinate and produce a pollen tube, which grows through the style and enter the micropyle of the ovule. The generative nucleus of the pollen grain must be set at liberty and unite with the oosphere in the embryo-sac. The union of these two nuclei is called fertilisation. + +(3) The oosphere after fertilisation is called an oosphere or egg-cell, and must develop into an embryo or young plant (p. 11). + +(4) Food materials must be removed from the leaves of the plant into the embryo, so that it may be used up by the developing embryo during its early growth or to be stored until the germination of the seed takes place. + +A diagram showing the process of pollination and fertilisation in flowering plants. + +CH. XVI +POLLINATION AND FERTILISATION +207 + +Pollination.--Pollination may take place in two different ways. + +(1) Cross-Pollination.--When the pollen of a flower is distributed to the pistil of another flower it is said to be cross-pollinated. + +(2) Self-Pollination.--When the pollen of a flower is distributed to the pistil of the same flower it is said to be self-pollinated. + +Cross-Pollination.--It has been proved with many plants that cross-pollination produces a better crop of seeds; and that the plants produced from these seeds are stronger and better able to resist disease than those produced by self-pollination out by the late Charles Darwin 3 those cross-pollinated flowers produce offspring which possess (a) greater strength, (b) the habit of earlier flowering, (c) greater diversity of colour, than the plants produced by self-pollination. These facts are illustrated in two ways -- + +(1) When the pollen is being carried from the anther of one flower to the pistil of another flower by insects. Those plants which possess flowers which are pollinated by insects are called entomophilous or "insect-cultivating" plants. + +(2) When the pollen is being carried from the anther of one flower to the pistil of another flower by the wind. Those plants which possess flowers which are pollinated by the wind are called anemophilous or "wind-cultivating" plants. + +Why Insects visit Flowers.--Insects are attracted to flowers by their shape, colour, and perfume. Many flowers also produce nectar, a sweet solution which insects drink, which produce honey which are called nectaries or honey-glands (p. 193). These nectaries occupy different positions in different plants. They may be on the upper surface of the petals, on the sepals, or at the base of the stamens, or in a cavity which occur at the base of the short stamens, and the sugar solution or honey which they produce is stored up in the sac-like receptacle formed by the sepals, or in modified petals, which are tubular in shape, bear nectaries. The nectary in the spotted orchid is in the twisted spur, and it is necessary for the bee to put its tongue or proboscis down this spur in order + +3 The Cross and Self-Fertilisation in Plants. + +208 +BOTANY FOR BEGINNERS +CHA.P. + +to reach the honey. In fact any part of the flower may be modified for the secretion and reception of honey. +Insects cannot live on honey alone for it contains no nitrogen, and nitrogen is necessary to all living animals as for plants. Many coloured flowers do not produce honey, but plenty of pollen, the pollen being collected by insects for their food. In the case of the honeysuckle, which produces its own honey, it contains nitrogen. Bees, for instance, possess small brushes, on the end of their appendages or limbs, which are used to brush off the pollen from the flowers they visit. The pollen is then moistened and rolled up into little balls, which are stored in a little sac in one of the limbs until the hive is reached. The Brood-Bees (Bombylius) are very fond of honeysuckle and are visited by crowds of bees for the sake of its pollen, which it produces in large quantities. Insects are of great importance to plants because they distribute the pollen from flower to flower, and the plants themselves are often pollinated by insects for their food. +**Contraindications to Prevent Self-Pollination.**—The im- +portance of cross-pollination to many plants has produced many contrivances in order that this may take place. It is only when more successful cross-pollination takes place. The principal arrangements by which flowers facilitate cross-pollination must now be described. +(1) The stamens and carpels may be produced in different flowers. In such a case it is necessary for the pollen to be carried from one flower to another before it can be used for fertilisation. The stamen-bearing flowers and the carpel-bearing flowers may be produced on the same plant, as in the Birch, Hazel, and Pine, or on different plants as in the Dog's Mercury and Willow. The bearing flowers may be produced on one individual plant, as in the Dog's Mercury and Willow, when the plant is said to be dioecious. +(2) Both stamens and carpels are present in most of the common flowers, and the flower is said to be monoecious. In such a case both stamens and carpels ripen at about the same time, and carpels ripening at different times. If the stamens ripen and distribute their pollen before the carpels of the flower bearing them are ready for pollination, the flower is said to be protandrous, as in the Dog Daisy, Safflower, and Harebell. + +xvi +POLLINATION AND FERTILISATION +209 + +When the carpels ripen and are pollinated before the stamens of the same plant are ready to distribute their pollen, the flower is said to be **proterogynous**, as in the Plantain (Fig. 213). + +(1) The stamens may be long and the stigmas short, as in the Cornflower and Primrose. The style of one flower may be long and the stamens short, and in another flower the stamens may be long and the style short. In this case, the pollen of one flower would reach the stigma of another, but the pollen of a long-styled flower and the pollen of a short-styled one would reach the stigma of a short-styled flower (p. 210). + +(2) The stamens may be short and the stigmas long, so that no effect on the ovules of the same flower, as in most Orchids. + +**Cross-pollination by Insects—We have seen that many insects are very useful in pollination. They also aid in the distribution of pollen from flower to flower. Most entomophytes plants produce flowers which have the following characters—*** + +1. They are brightly coloured, sweet-scented, and very prominent. +2. They produce honey and pollen, or pollen only, the insects visiting them being attracted by these substances. +3. They produce pollen-grains which are generally sticky so that they will adhere to the body of insects and to the stigma. +4. They are placed so that insects must brush through them as they pass into the flower in search of honey or pollen. + +We will now consider how cross-pollination is produced by insects. + +1. **Dimerous Plants—If the flowers from a few Cowslip plants are examined the stamens in one will be found at the top of the tube, and in another half-way down the tube. In another specimen the stamens will be at the top of the tube, and the stamens half-way down the tube. The first flower has short style and short stigma, while the second has long style and short stigma. The Cowslip, and all other plants the individual flowers of which vary in the lengths of their styles and stamens, are said to be heterostylid. If there are only two lengths of style in the plants they are called dimerous. (See Primrose, p. 268.)** + +P + +210 +BOTANY FOR BEGINNERS +CHAP. + +Expt. 185.—Collect a few flowers of the Cowslip or Primrose and examine them carefully. The flower is composed of two sepals, two petals, one corolla tube, and another where the stamens occupy a similar position. Open each corolla by inserting a knife at the bottom of the tube, and making a slight incision on the upper side. The style is long, and the stigma is short. +Note—(i) The stamens are half way down the tube, and the style at the top of the corolla tube. +(ii) On the short-styled one, note, +On the long-styled one, note, +(iii) The style is half way down, and the stamens at the top of the corolla tube. +Place the flowers side by side, and measure the relative lengths of stamens and stamens, note, +(iv) The long-styled is on the same level as the stamens in the short- +styled flower, and the stamens in the long-styled flower are on the same level as those in the short-styled. +(v) The honey which is at the base of the corolla tube. +In the long-styled flower, the pollen grains are different, and the structure of the tip of the stigma varies. The differ- +ence of the two flowers is seen below in a tabular form. +Long Style Short Style +Flowering... A little later Earlier +Stamens... Short Long +Pollen... Grams smaller Grams larger +Style... Globular hairs long Flattened hairs short. +The larger pollen grains of the short-styled flowers are necessary because they have to pollinate the long-styled flowers, and a longer pollen tube is required to reach to the ovary. Thus they contain materials for the production of a longer pollen tube. The longer hairs on the stigma of the long- +styled flower prevent the pollen grains from being blown +away by the wind. +The Word of the Insect.—When the insect visits the Cowslip or some other plant with long-styled flowers, it may find a corolla to reach the nectary at its base. If a flower is a long- +styled one, the tongue is dusted with pollen at a certain point, and if this happens to be near a stigma, then that stigma is +placed on the top of the flattened stigma. In the short-styled +flower the tongue of the insect is dusted with pollen higher up; +this is deposited on the stigma of the long-styled flower. Thus +the prothorax of the insect is medium for the distribution of +the pollen, and so produces cross-pollination. + +XVI +POLLINATION AND FERTILISATION +211 + +This description will do for most dimorphic plants, among which the Primrose, Lungwort, and Common Fox-axe are examples. + +A. Trimorphic Plants.--If a few flowers of the Purple Loosestrife are collected from different plants and examined they will be found to be heterostylic, and in addition trimorphic, i.e., with three distinct styles and stigmas. The following is a diagram of the styles and stigmas is seen from the following description :- +(A) Flowers, where the stamens are in two sets—a short set and a long set. +(B) Flowers, where the stamens are in one set of the same length as the short stamens, and another of the same length as the style in A. +(C) Flowers, where the stamens are in two sets—one set on the same level as in the long style in B, and the other set level with the style in A. The style is shorter than the two sets of stamens. +Thus, there are short-stylae, medium-stylae, and long-stylae. There are short-stamens, medium-stamens, and long-stamens (Fig. 210). + +Fig. 210.--Collect flowers of the Purple Loosestrife from different plants. They can be found in damp places in July and August. Examine them. Note-- +(1) The calyx is calyce, near the top of which the distinct, +crumpled, purple petals are inserted. +(2) Below these petals is a calyx tube, but much lower down than the petals. +(3) The corolla is trimerous (p. 160) flat of two carpus, which possesses one style and one stigma. +Now dissect with care a number of the flowers, and arrange them into three series according to the comparative lengths of the stamens + +P 2 + +212 +BOTANY FOR BEGINNERS +CHAP. +and stigmas. Separate the petals from the calyx, and open the tube of the calyx so as to show the position of the stamens and stigma. +Note: +(i) Those flowers where the stigma comes between the two sets of stamens, are called perfect flowers. +(ii) Those flowers where the stigma is long—the two sets of stamens come together at the base of the flower, and are separated by a short-length. +(iii) Those flowers, where the stigma is short—the two sets of stamens are inserted above it. The stigma is short—the stamens are of mid-length. +Now mount pollen from the different sets of stamens in water. Examine with low power. Measure the size of each, and note which are the largest and smallest. +(viii) The pollen grains from the long stamens of the short-styled form are large and round. +(ix) The pollen grains from the shortest stamens of mid-styled form are small and oval. +The Work of the Insect—In a plant of this description the pollen is distributed by insects. From the examination of the flowers it is seen at once that the insect cannot reach all parts of the flower. It can only reach (i) the long stigmas; from the mid-stamens to the long-stigma; (ii) from the mid-stamens to the short-stigma; (iii) from the short-stamens to the long-stigma; (iv) from the short-stamens to the short-stigma. +Clyd +3. British Orchids.—The most highly developed of all entomophytes plants are the orchids. They are noted for their peculiar beauty, and for their great variety. Representatives of this order of plants are found nearly all parts of the world, and men are constantly engaged in collecting them, looking for new specimens. One of the common British representatives is the Spotted Orchis, which makes gay many land and sea-cliffs, and decorates Sussex Downs and most sea-cliffs in the South. + +Expt. 187.—Dig up a single plant of the Spotted Orchis when in flower, and examine it carefully. +(i) From its tuberous root sieve several smooth, parallel-veined, spotted leaves. +(ii) From its centre of the leaves springs the peduncle, which bears a narrowly pyramidal head of many purple flowers. +(iii) From this head fall off one after another of the flowers and hold it in the same position as that assumed by it when on the stem. + +Fig. 117.—Floral Diagram of Orchid. +gram of Orchid. + +xvi +POLLINATION AND FERTILISATION +213 + +twisted stalk to all approaching contacts to the peduncle. Cut across this supposed stalk - it is full of mucus - and see, it is the ovary. +Now examine the flower, it is symmetrical (p. 19). Note: +(1) The sepals are equal, and the petals are unequal, the superior (p. 183). The largest leaf of the petal is called the labellum, and is somewhat like a tongue, with a broad base, and a narrow apex, a metarix. + +In the single stamen, the anther of which is united with the pistil, and is consequently said to be gynandromorph. The stamen terminates below by a short stalk, and is inserted into the cavity formed over the opening into the spur, so that an insert must push its one side into the cavity of the other. This is seen in fig. 50. + +(2) The ovary, at the top of which the shiny, sticky stigma is seen. +This is produced by the root-mass which has been extracted. +The pollen-masses can be extracted in the following way : With a fine pointed pencil press the root-stem, and keep it pressed for about half an hour. Then take out the root-stem, and with this tip of the pencil the pollen-masses which have been extracted from the root-stem will fall off on to your hand. These masses are erect, but at the end of two or three minutes they incline forwards, and then lie flat upon your hand. When you touch these flower they strike the stigma, and some of the pollen will adhere to them. + +The flowers of the Spotted Orchis are splendidly adapted for cross-pollination. The insect which visits this flower brings a quantity of pollen which will obtain the maximum of results. If a bed of this plant is watched on a bright day in June or July, the bees and flies are attracted by the flowers for food, and if these insects are caught and examined after their visitation it will be seen to adhere to their heads. + +The Bee Orchis - The bee or other insect which is attracted to the Orchid flower lands upon the labellum on the lower side of the flower. He passes his proboscis down into the spur in search of honey. The head of the insect thus comes in contact with both sides of the spur, and when he leaves it, and the bee's head now rests against the anther. The base of the anther is covered with a sticky secretion which adheres to him, and begins to set there. This process takes place in several seconds at least. The time necessary for this to take place is gained by the honey being stored up in the thickness of the wall of the spur. The pollen-masses are then forced in and penetrate the walls of the spur. This takes time, during which the pollen-masses set on the head of the insect. When the honey has been extracted, the inserts fly away with the pollen-masses, which change their position, as they did on + +214 +BOTANY FOR BEGINNERS +CHAP. + +pencil ; and when the next flower is visited, they come in contact with the stigma and pollinate it. +—*Flowers Pollinated by the Humble-Bee.*—Flowers like the Clover, Vetch, and Pea are pollinated by the humble-bee possessing a long tube-like proboscis. In flowers of this description the honey is stored deep down the tube formed by the diadelpheous (p. 183). stamens. + +EXPR. 188.—Obtain a few inflorescences of the Clover and examine them. +Note: +(i) The inflorescence is a head of numerous flowers. +(ii) Each flower is zygomorphic (p. 179). +(iii) The corolla is tubular (p. 180). +(iv) The corolla is polygamous (p. 183), and consists of a standard, two wings, and two keels. +(vi) The stamens are diadelpheous (p. 183). +(vii) The pistil is monocarpous (p. 185). +(viii) The free standard and small opening down which the humble-bee can enter. +(ix) If the standard is pressed downwards, the nectar is discharged to the pollen in a certain way. +(x) The honey can be extracted from the nectary at any time of the year formed by the stamens. + +**Cross-pollination by the Wind.**—A large number of plants are pollinated by the wind. They include, among others, the Grapes, the Hazel, Yew, Oak, and Plantain. +The chief characteristics of wind-pollination are : +1. The flowers are small, simple, and inconspicuous, thus presenting a great difference to the brightly-colored flowers with their stamens and pistils. +2. The flowers have no scent and do not secrete honey ; in fact, they have none of the characters by which the entomophous flowers attract insects. + +Fig. 225.—Influence of Plant-voice on Wind-Pollination. +The upper flower is seen closed, and the lower one open. When these flowers have lost their stamens and pistils, +and do not secrete honey— + +A diagram showing two flowers: one closed and one open. + +and do not secrete honey— +in fact, they have none of the characters by which the entomophous flowers attract insects. + +xvi +POLLINATION AND FERTILISATION +215 + +3. The flowers produce great quantities of pollen, which is powdery and can easily be distributed by the wind. +4. The versatile anthers are fixed on to slender filaments, which are covered with fine hairs, so that they can shake them. (Fig. 212) The Nette, for instance, can distribute its pollen with the wind by uncurling its filaments with a sudden movement, so that the pollen is mixed with the air. The stigmas are large and possess structures for holding the pollen which comes in contact with them. (Fig. 212) + +Comparison of Insect-Pollinated and Wind-Pollinated Plants. + + + + + + + + + + + + + + + + + + + + + + +
Insect-Pollinated Plants.Wind-Pollinated Plants.
1. The pollen is carried in a definite direction, i.e., from flower to flower.1. The pollen is carried in all directions, and the green bulk of the plant is exposed to the wind.
2. Less pollen is produced, for it contains certain of these plants.2. Large quantities of pollen are produced, because they reach the stigmas of a flower.
3. The pollen is pre- tected from rain, dew, and marauding insects.3. The pollen is used in producing pollen.
4. Less material is used in producing pollen.4. A greater number of seeds are produced with the minute quantity of material used in producing pollen.
+ +Self-Pollinated Plants.--By self-pollination is meant where the pollen of a flower A pollinates the stigma of the same flower A. There is a number of plants which produce flowers that are self-fertile, i.e., those which do not need to be secured, and seem in these flowers to give good results. The self- pollinated plant is more likely to be pollinated than any other, because it has no need to travel far to find another flower for the purpose of bringing about fertilisation. This is due to the slight movement to bring it on to the stigma. Either the wind or insects may produce self-pollination, by distributing the pollen from the anthers to the stigma. Several flowers, which are near each other, may be pollinated at once, but this does not usually happen until the pollen-laden anthers are reached and self-pollination takes place. The Poor-man's Weatherglass produces flowers which may be cross-pollinated during the first three days after opening; but not pollinated during this interval, the flowers + +216 +BOTANY FOR BEGINNERS +CHAP. + +close up and never open again, but the anthers come in contact with the stigma and self-pollination takes place. +A very large number of plants produce masses of flowers—-the ordinary flowers being closed upon one another. +The small closed flowers, called Cleistogamous flowers, are self-pollinated and produce large quantities of seeds. The structure and advantages of these flowers will be discussed later on. +**The Structure of Cleistogamous Flowers.** They are very small and never open. The petals are rudimentary or absent, but the sepals are usually present. The stamens are few, producing their tubes while in the anthers, the pistil is small, and the stigma almost absent. Pollination takes place by means of insects which, from the anthers down the short style to the ovules in the ovary. +**Advantages of Cleistogamous Flowers.** They seem to furnish the following advantages: +1. They produce seeds in seasons when the ordinary flowers which are insect-pollinated might be able to produce none. +2. They produce seeds with the smallest consumption of matter, since they do not need to attract insects for pollination. The amount of pollen used in the cleistogamous flowers of the Violet is only the 24th part of that used by a Dandelion, just as many seeds being produced as in a perfect flower of the Violet. +3. They belong to plants which also produce zygomorphic flowers (see page 180). In some species, however, in this strange climate of ours, are very variable quantities. Hence seasons might occur, and do occur, when the necessary insects not being present no seeds would be formed but for the cleistogamous flower. +Among the plants which produce cleistogamous flowers are the Weeds. + +**Fertilisation.** When the pollen grains are deposited on the stigma, they are generally held fast by its sticky surface. The grains take up moisture and nutritive materials from the stigma, and then pass between the superficial cells of the stigma and bore their way down the style. They feed, as they grow, upon the tissue of the style, and enter the ovary. In the ovary they find their way to the micropyles of the ovalets. Each + +xvi +POLLINATION AND FERTILISATION +217 + +ovule requires one pollen grain to form a tube to bring its generative nucleus to the oosphere. Why the pollen tubes enter the micropyle is not fully understood at present, but there must be some stimulus which causes this. + +The pollen tube is guided, to the oosphere by the egg-apparatus (p. 203), the tip of the tube is broken off, and the pollen tube becomes a vacuole so that the pollen grain is set at liberty. The liberated generative nucleus fuses with, and fertilises, the oosphere. + +In the process of pollination of the pollen grain and tube enables all the stages in the production of a pollen tube and in the process of fertilisation to take place. The pollen tube passes into the pollen tube first, then the generative nucleus follows on. The vegetative nucleus remains behind in the pollen tube, and the generative nucleus or cell divides into two. When the micropyle is reached, the tube passes in between the egg-spermatozoa and fuses with them. At this end of the tube along with some of the protoplasm. The nucleus travels on until it reaches the nucleus of the oosphere, when it fuses with it, thus completing fertilisation. After fertilisation, the oosphere becomes an embryo sac or egg-sperm, and it surrounds itself with a firm cell-wall. + +Development of the Embryo.--The development of the embryo can be studied in a little way seed, the Shepherd's Purse (Capsella bursa-pastoris). This plant has very large number of seeds, and as a rule, all stages can be obtained on one plant, from the oosphere up to the mature embryo. + +The stage of fertilisation is called fertilisation. The part of the micropyle which is occupied by the spermatozoon is called the upper cell. The upper cell produces a row of cells called the suspensor ; the lower cell by division gives rise to nearly all the embryo. The suspensor supports the embryo by means of its long filaments. The upper cell, lower cell divides into eight cells. The four which are nearest to each other give rise to two cells only, while those which are furthest away give rise to three cells each. These three cells are called cotyledons and plumule. The four corners of the suspensor form the radicle. The tip of the radicle and the rootlet are formed by the upper cell of the + +Fig. 285.--PT., polen tube; PT., pollen tube; PT., pollen tube; PT., pollen tube. +PT + +218 +BOTANY FOR BEGINNERS +CHAf. + +suspensoir. (Fig. 214.) The outer cells of the embryo, as it can be called, divide up to form the dermatogenes (p. 112), which forms the whole epidermis of the shoot. The inner cells divide up to form the plerome, by which the cylinder of the main stem is formed. Cells are separated between the dermatogenes and plerome, from which the cortex is produced. These form the periclum. + +ExrT. 35a.—From the Shoots of the Cynara (Fig. 215).—The shoot contains a number of ovaries in different stages of development. Remove the outer epidermis, and with needles separate some of the ovules from the integuments, showing the dividing wall of the ovary. Soak them in potash solution for ten minutes, and they will appear almost transparent. + +Mount one ovule in deep glycine on a slide and place on it a cover-glass, so as to give the cover-glass a sudden tap, to burst the cell walls and allow out the embryos. Use the lower power of the microscope at all stages and for the younger ones only. +Note.—The thylacium, which consists of several cells, at the end of which the embryo is formed, is very delicate and may easily be broken. + +(ii) The embryonic cell in an older specimen will have divided into a number of cells. + + +A B C D E F G H I J K L M N O P Q R S T U V W X Y Z + + +Fig. 214.—Stage in the development of embryo of the Shepherd's Purse, *Capsella bursa-pastoris*, placentae et suspensio ir., Symplocaceae. (Magnified.) +35 + +xvi POLLINATION AND FERTILISATION 219 + +(iii) In still older specimens the cells have become so arranged that the following layers can be seen: (a) Dermatogen, covering most of the embryo; (b) plerome, forming the central mass of the embryo; (c) two layers of cells. + +In still older stages the cytoplasm will have appeared. They will be seen as hillock-like growths on the upper part of the embryo. + +Expt. 199.—Collect a few inflorescences of the plant. (1) The flowers are in full flower in June, July, and August. Remove them from the plant. Note their colour. Remove some of the ovaries, and test for the presence of starch by means of glycerine, and with the cover-glass force out a piece of the ovary. + +(ii) The suspensor and embryonic cell. + +(iii) The embryonic cell divides up into four cells. + +(iv) The cells divide into dermatogen, pleurogen, and hypoblast. + +(v) Try and make out the following structures: + +(a) The single cytoplasm which is formed from the suspensor and embryonic cell. + +(b) The radicle and apex of root which are formed from the two outer cells. + +Changes in Embryo-Sac. +During the development of the embryo, bryopsis takes place in the embryo-sac, and it produces a number of nuclei. When hundreds of nuclei have been produced, and the embryo-sac has been enlarged, cell-walls begin to be formed between these nuclei. These cell-walls are first produced in the embryo-sac, in which starch and proteins form in the proplastids. The aleurone grains are stored up for the use of the embryo. This tissue receives the name of endosperm. In Wheat, Barley, and Rye, this process is very well marked. It is remarkable that it is not used up in the development of the embryo, but is utilised when the seed germinates and the embryo begins to grow. The endosperm is therefore said to be albinous. If the endosperm is all used up by the developing embryo, so that the embryo-sac is filled with the embryo, the seed is said to be exalbuminous. Wheat, Barley, and Rye are + +Fig. 211.—Young embryo of Triticum vulgare. The cytoplasm is showing a bryopis. +211 + +220 +BOTANY FOR BEGINNERS +CHA.P. + +examples of albuminous seeds, and Peas and Beans of exalbum- +inous seeds. In a few cases, reserve material is formed from the mescula (p. 201), which is around the embryo-sac, when the tissue formed is called *xerofitum*. Examples—Hempseed and Figs. +Results of Fertilisation. The fertilisation of the oosphere has far-reaching results. These are shown below in a tabular form. +1. The oosphere is converted into an oospore, from which, by development, the embryo is produced. +2. The pollen-grain becomes a sporophore, which may be used up by the developing embryo or stored up until the seed germinates. +3. The zygote is converted into a seed. +4. The ovary is converted into a fruit. + +SUMMARY. +Fertile Plants differ from non-flowering plants in the production of seeds. +Seeds are formed from seeds by the changes which go on after fertilisation. +Fertilisation is the distribution of the pollen from the anther to the stigma. It can take place in two different ways—(i) Cross-fertilisation, when the pollen comes from another plant of the same species—(ii) Self-fertilisation, when the pollen of A finds its way to the stigma of B. In some plants, self-fertilisation is impossible—(a) The flowers may be dichogamous (p. 200); (b) the plants may be monoecious or dioecious (p. 200); (c) the flowers may be perfect or imperfectly gynous (p. 200); (iii) the plant may produce two or three kinds of flowers—perfect, imperfect, and sterile—(iv) Pollen is often carried by insects—(v) Pollinated: Pollenated flowers are—(i) Brightly coloured, sweet scented, and very prominent; (ii) they produce either honey, or plenty of pollen, or neither; (iii) they are large or small; (iv) small. +Trimerous Plants produce two kinds of flowers; these are—(i) Flowers with short-styled; (ii) Flowers with long-styled. +The pollination of Trimerous Plants consists in one kind of the long-styled form, and the pollen of the long-styled flower the stigma of the short-styled flower. +Trimerous Plants produce three kinds of flowers; these have three lengths of style—(i) Trimerous: Flowers, such as the Clover, Vetch, and Funa, cannot be pollinated by any other insect because their tongues are not long enough. +Wind-Pollinated Plants produce flowers which possess the following characters—(i) The flowers are small, and generally green; (ii) the + +xvi +POLLINATION AND FERTILISATION +231 + +flowers have no scent (ii) the flowers produce great quantities of pollen which is dry (iv) the anthers are versatile and hang out of the flower (v) the stamens are long. + +Self-Pollinated Plants produce flowers which may be--- +(i) Pollinated by the wind blowing the pollen from the anthers to the stigma. +(ii) Pollinated by insects creeping over the flowers and distributing the pollen on their bodies. +(iii) Pollinated by the wind blowing the pollen from the anthers to the stigma. +(iv) Pollinated by the stigma coming in contact with the anther of another flower. + +Non-Pollinated Plants produce generative meconium of the pollen grain with the coelophore in the ovule. + +Pollination is effected by an agency other than by division. + +The Sexes of Fertilisation are--- +(i) The antherule changes into the coelophore. +(ii) The coelophore becomes a pollen sac. +(iii) The embryo-sac is filled with a tissue—the endosperm. +(iv) The ovary is converted into a fruit. + +QUESTIONS ON CHAPTER XVI. + +(1) Explain, giving examples, the meaning of the following terms— +a. pollination +b. fertilisation +c. self-fertilisation +d. cross-fertilisation + +(2) What is meant by self-fertilisation and by cross-fertilisation? Mention two examples of each. + +(3) Describe the structure of the flower of any British Orchid, and explain how pollination takes place. (500.) + +(4) Describe how insects are not pollinated by insects, and explain in what respects they differ from flowers which are pollinated by insects. Give examples of both kinds of flowers. How do these flowers differ. (1984.) + +(5) Describe how insects which attack plants are of use to flowers, and the means by which flowers attract them. + +(6) How do insect-pollinated flowers differ from insect-destroyed flowers? Give examples of both. (586.) + +(7) How do wind-pollinated flowers differ from insect-pollinated flowers? Explain why some flowers are differently coloured, and (d) irregular flowers, as compared with (c) inconspicuous and (e) regular flowers. Give examples. + +(8) What is meant by the spur formed from floral leaves? Give examples. + +(9) What is meant by heterostylous plants? Give examples. + +(10) Mention plants which produce climatogenic flowers, and explain how they differ from ordinary flowers. (586.) + +(11) How do dimorphic plants differ from monomorphic plants? Explain why some plants have one form and others have two forms. (586.) + +(12) Why are the pollen-grains larger in the short-styled flower of the Primrose than in the long-styled form? + +A diagram showing different parts of a flower. + +CHAPTER XVII + +THE MORPHOLOGY OF SEEDS AND FRUITS, AND THEIR DISTRIBUTION + +**Seeds.**—A seed is the result of the changes which take place in an ovule after fertilisation. The changes can be shown thus: + +(1) The oospore develops into an embryo. + +(2) The embryo-sac nucleus divides up to form endosperm. + +(3) The coverings or integuments of the ovule change and become the outer coats of the embryo, and in the seed are called the spermoderm (p. 11). + +**Structure of Seeds.**—Each seed is covered with a layer, the testa. It is formed from the integuments of the ovule. The central portion of the seed is formed by the embryo and the endosperm, both of which are present. The opening through which water enters is called the micropyle (p. 18), and represents the micropyle of the ovule. The parts present in albuminous and exalbuminous seeds may be shown thus: + + + + + + + + + + + + + + + + + + +
Albuminous.Exalbuminous.
Testa.Testa.
Embryo.Embryo.
Endosperm.Endosperm.
+ +**Comparison of an Ovule with a Seed.**—The corresponding parts of the ovule and seed may be easily compared:— + +A diagram showing the structure of a seed, including its layers and components. + +CH. XVII MORPHOLOGY OF SEEDS AND FRUIT + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Ovule.Seed.
Funiculus.Funiculus.
Integuments.Testa.
Micropyle.Micropyle.
Nucellus.Perisperm.
Embryo-sac.Embryo-sac.
Contents of sac.Embryo and Endosperm.
+ +**Examples of Various Kinds of Seeds.** Some examples of the different kinds of seeds will be useful. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Ambrosia.Eriophorum.With Peripheron.
White Oak.Pine.Stellaria.
Barley.Bean.Piper.
Vetch.Water Lily.Henbane.
Rye.Apple.Water Lily.
Tall Grasses.Cornet.Henbane.
All Grasses.Oak.Henbane.
+ +The **Aril**—The seeds of some plants have appendages which may be variously produced from the funiculus, hilum, or micropyle. Such new growths are called arils. In the Willow-both the aril and the seed are produced from the same portion of the seeds. In the Water Lily the aril is produced from the funiculus, and grows round the seed, producing an outer cover- ing, which is often very thick. The aril is a modification of the formation of an aril also takes place in the Yew and Passion flower. In the seed of the Castor Oil plant the aril appears as a tuft of woolly hairs formed from the funiculus, and hence called a funiculus aril. Among other plants which produce an aril are Milkweed, Violets, Celandine, and Spindle-tree may be mentioned. + +Expt. 191.—Examine the structure of the seeds given in the table on p. 223. Note— + +(i) The position of the hilum and micropyle. +(ii) The nature of the hilum either albuminous or exalbuminous. +(iii) The nature of the endosperm. +(iv) The number of cotyledons present. + +(v) The number of cotyledons present. + +224 +BOTANY FOR BEGINNERS +CHAP. + +**Fruits.** -Fertilisation not only stimulates the ovule and its contents so that a seed may be produced, but its influence also extends to the whole flower, and other parts of the flower, so that a fruit is formed. Other parts of the flower which do not take part in the formation of the fruit drop off soon after fertilisation has taken place. The fruit is thus the direct result of the changes which go on in a flower as a result of fertilisation. + +**Definition of a Fruit.** -A true fruit is the result of the changes which go on in a single gynaeceum due to fertilisation. When other parts of the flower take part in the formation of + +A: A; B: longitudinal section of Apple; C: transverse section of Apple. + +Fig. 216.-A; Apple; B, longitudinal section of Apple; C, transverse section of Apple. A, anterior mericarp ; B, anterior mericarp ; C, posterior mericarp. + +the fruit, the organ produced is called a *friurious fruit* or *parasidose*. The apple is formed by the receptacle growing up round the ovary and enclosing it, and forming with it the whole of the succulent part of the fruit. When an apple is used as food, it is the altered receptacle and calyx which we eat, while the core is left behind and is called the *core*. The *pips* are the seeds. (Fig. 217.) + +In the strawberry the receptacle becomes succulent after fertilisation, and encloses all the fruits which grow in it. In which which fruit contains (Fig. 217). Fruits can thus be divided according to the parts of the flower which take part in their formation into true fruits and friurious fruits. + +**XVII** MORPHOLOGY OF SEEDS AND FRUIT 225 + +**Structure of a Fruit—** The wall of the fruit is called the pericarp, and in most instances it can be divided into three different layers: + +The **exocarp**, or outer layer of the fruit. (Fig. 218). The **mesocarp**, or middle layer of the fruit. + +The **endocarp**, or inner layer of the fruit. + +The pericarp may be hard and dry, or soft and succulent. In the Apple, the exocarp is succulent and the remainder hard. In the Plum and Cherry the epicarp and mesocarp are succulent, and the endocarp is hard (Fig. 218). The exocarp of the Apple is easily broken off when the seed within is used for food (Fig. 221). + +When the fruit is formed from a single carpel, as in the + +Aac A' B' +Fig. 218.—A, Strawberry; B, longitudinal section of Strawberry; Ac, carpel; A', B', walls recombined. + +Bean and Pea, it is called a *monocarpous* fruit. If two or more separate carpels take part in the formation of the fruit, as in the Buttercup and Raspberry, the fruit is *dicarpous*. A *syncarpous* fruit is one formed by a number of syncarpous gynaeceum, as in the Poppy, Lily, and Willowflower. + +Fruits may dehisce or open to liberate the seeds, when they are called *dehiscent*, or remain closed until the mature seeds, but the seeds germinate within, and the young plant break through the wall of the fruits, they are called *influent*. + +When the fruit is the result of a single gynaeceum it is called a *simple fruit*, and when produced from a number of carpels it is said to be a *compound fruit*. Thus, both monocarpous and syncarpous fruits are simple, while apocarpous fruits are compound. + +Q + +236 +BOTANY FOR BEGINNERS +CHAP. + +**Expt. 192.—Select a ripe Cherry and examine it. Note—(i) The flesh is white and juicy. +(ii) Just below the fruit a scar is present; this is where the stamens were removed. +(iii) Just on the top of the fruit a small spot is present; this is where the style was fixed. +(iv) The cherry cannot be a true fruit because it is formed from the gymnocarp only.** + +**Cut a Cherry across. Note—(i) The hard part in the middle; the hard part is the endocarp. +(ii) The outer part of the fruit is the epicalyx, and the inner is the mesocarp.** + +**Cut a Cherry in half. Note—(v) The seed in the centre; it is protected from injury by the hard mesocarp.** + +**Cut a Cherry in quarters. Note—(vi) Stone fruits like the Cherry, Plum, and Peach are called **drupes**.** + +**Expt. 193.—Obtain a ripe Gooseberry and examine it. Note—(i) At the top of the fruit the dried-up lobes of the calyx open. This shows that—** +**(ii) The fruit is succulent, and when ripe the pulp can be forced out. Note—** +**(iii) The fruit is one-celled, and the cavity is filled with juicy pulp containing seeds.** +**(iv) All fruits which are succulent and succulent, and do not open to release their seeds, are called drupes.** The fruits of the Red and Black Curtains and Grape are true berries. + +**Expt. 194.—Obtain a Poppy head from a chemist and examine it. Note—** +**(i) The external markings on the fruit: these represent the carpels from which the syncarpous fruit was formed.** +**(ii) The ovary is covered through pores which are near the apex. When fruits liberate their seeds by pores, they are said to be dehiscent.** +*Note—* New coat across the fruit. Note—** +**(iii) The core is one-celled and contains many seeds.** +**(iv) A dry syncarpous fruit which dehisces by pores, valves, or teeth is called a capsule.** + +**Expt. 195.—Examine an Apple. Note—** +**(i) The top of the lobes of the calyx on the top of the fruit: The fruit is indurated.** +*Note—* New coat across the section of the Apple so as to pass through the dried lobes of the calyx and the pericarp.* Note—** +**(ii) The skin, which is peeled off when the Apple is eaten, is the epicarp.** +**(iii) The succulent part of the pericarp, which is eaten, is the mesocarp.** +**(iv) The core is the endocarp and contains the seeds.** + +A diagram showing a cross-section of a cherry. + +XVII MORPHOLOGY OF SEEDS AND FRUIT 227 + +(5) The calyx tube, or receptacle, has grown up and surrounded the gynoecium, thus forming a subarum fruit. The quincus fruits like the Apple are called pomes. + +Examine a number of Strawberry in different stages of development, and examine them. Note— + +(i) The ripe Strawberry consists of a pulpy mass which is surrounded at its base by a calyx tube. +(ii) The surface of the fruit is covered by numerous small bodies which form a sort of net-work over the surface of the fruit. This style or shows the scar where the style was fixed. +Note—The calyx tube is very thin. +(iii) The least ripe Strawberry will have a very small receptacle, with a few small seeds in it. As the fruit ripens, the fruit of the Strawberry is spurious, and is formed by the receptacle occurring successively. +(iv) It is an apocarpous succulent fruit. + +Exrrt. 197.—Examine a Blackberry and compare it with the Straw- +berry. Note— + +(i) The Blackberry consists of a number of succulent droplets, which are arranged in a circle around the receptacle. +(ii) Each droplet contains a seed. +(iii) The receptacle of the Blackberry is in having the carpell succulent instead of the receptacle. +(iv) In the Blackberry is an apocarpous fruit, and may be called a compound fruit. + +Classification of True Fruits.—Fruits can be arranged according to the characters of the ripe pericarp into— + +(i) Succulent fruits (simple), when some portion or the whole of the pericarp is succulent. + +Fig. xx.—A, Plum ; B, longitudinal section ; C, transverse section. $E$, epicarp ; +$M$, mesocarp ; $E_n$, endocarp ; $S$, seed. + +(a) The drupe, when the epicarp and mesocarp are succulent, but the endocarp is hard and stone-like (Fig. 218). Examples— + +Cherry, Plum, Peach, and Apricot. + +Q 2 + +28 +BOTANY FOR BEGINNERS +CHA. +(3) The berry, when the whole of the pericarp is soft and succulent (Fig. 219). Examples—Gooseberry, Grape, Current, Orange, and Cucumber. + +A B C +Fig. 219.—A, Gooseberry; B, longitudinal section; C, transverse section. + +Collective Fruits.-(c) The compound drupelet, when the carpels of an aecious gynaeceum are succulent, separated, and each contains a seed (Fig. 220). Examples—Black-berry and Raspberry. +(2) Dry fruits, when the pericarp is hard and dry. If they do not open to separate the seeds they are indehiscent; if they open, they are dehiscent. + +A B +Fig. 220.—A, Black- +berry. + +A B +Fig. 221.—A, Group of Hard-fruit; B, longitudinal section of fruit. (One-half nat. size.) + +Indehiscent Fruits.-(c) The nut is hard, inferior and syncarpous (Fig. 221). Examples—Acorn, Hazel-nut. +(3) The achene is hard, superior, and consists of one carpel (Fig. 222). Examples—Buttercup and Rose. +(c) The achene is a many-seeded fruit, which splits into + +XVII MORPHOLOGY OF SEEDS AND FRUIT 229 + +many one-seeded fruits, and these enclose the seeds until germination (Fig. 223). Examples—Fool's Parsley, Maple, and Geranium. + +a +b +c + +Fig. 223.—Achenes of Buttercup. (8.) Fig. 223.—Schizocarp of Symphoricarpos. + +Dehiscent. (a) The capsule is a dry, syncarpous fruit which opens by pores, valves, or teeth (Fig. 224). Examples—Poppy, Liliopsida, and other plants. + +A +B +C + +Fig. 224.—A. Capsule of Poppy; B. Syncarpous section of capsule ; C. Seeds. (See fourth note, side 3.) + +(b) The silique is formed of two carpels : i. t is superior and syncarpous (Fig. 226). Examples—Wallflower, Rape and Mustard. +If the silique is short and wide it is called a Silicula. Example—Shepherd's Purse (Fig. 227). +(c) The legume or pod is composed of a single carpel which + +230 +BOTANY FOR BEGINNERS +CHAP. + +dehisces along both the ventral and dorsal sides (Fig. 225). Examples—Pea, Bean, Vetch, and Clover. +(a) The follicle consists of a single carpel which dehisces + +A B C +B C D E F G H I J K L M N O P Q R S T U V W X Y Z + +A B C D E F G H I J K L M N O P Q R S T U V W X Y Z +B C D E F G H I J K L M N O P Q R S T U V W X Y Z +C D E F G H I J K L M N O P Q R S T U V W X Y Z + +A B C D E F G H I J K L M N O P Q R S T U V W X Y Z +B C D E F G H I J K L M N O P Q R S T U V W X Y Z +C D E F G H I J K L M N O P Q R S T U V W X Y Z + +A B C D E F G H I J K L M N O P Q R S T U V W X Y Z +B C D E F G H I J K L M N O P Q R S T U V W X Y Z +C D E F G H I J K L M N O P Q R S T U V W X Y Z + +A B C D E F G H I J K L M N O P Q R S T U V W X Y Z +B C D E F G H I J K L M N O P Q R S T U V W X Y Z +C D E F G H I J K L M N O P Q R S T U V W X Y Z + +along the ventral side only (Fig. 228). Examples—Columbine, Aconite, Poenya, and Larkspur. + +EXPT. 108.—Collect a few Hazel-nuts and examine one. Note— + +(i) The hard, dry pericarp which encloses the seed. +(ii) The thin, membranous outer layer, known as the三层which represent the epidermis, mesocarp, and endocarp. +(iii) The fruit is syncarpous and indehiscent. + +Fig. 226.—A. Fruits of Pistacia terebinthus.
B. Pistacia terebinthus., silique open.
C. Silique closed. +Fig. 227.—A. Fruits of Sphenoclea zeylanica.
B. Transverse section across B. +Fig. 228.—A. Follicles of Isatis tinctoria.
B. Transverse section across B. + +XVII MORPHOLOGY OF SEEDS AND FRUIT 231 + +**Expt.** 199.—Collect a few fruits from the Broom and examine them. +Note— +(i) The fruit is superior, and often bears at the tip the remains of the seed. +(ii) The top of the stalks bears the remains of the calyx, +(iii) The calyx is very narrow, and will split open along both sides, or +survive, (iv) The fruit is a ligulate. + +**Expt.** 200.—Collect a few full-blown Buttercup flowers and examine the fruit. Note— +The fruit consists of a number of carpellar. Each carpet is dry, +inhibident, and contains a single seed. +Fruit of the same plant, but different species, Aconites. + +**Distribution of Seeds.**—Just as the variety of colour, form, and perfume of flowers have to do with the distribution of the pollen, so the variety of texture, colour, and shape in fruits have to do with the distribution of seeds. From this it appears that in the struggle for existence, it is necessary that the seeds should be distributed as widely as possible from the parent plant. When in any particular case it has been found that seeds produced can possibly find suitable conditions for germination, it will be realised that the distribution of seeds is an important factor in their survival. + +The fact that seeds are distributed from place to place is shown by plants springing up in unlikely localities, such as rock-strewn hillsides, or on sand dunes. In examining the top of a church, a number of the seeds of the Sycamores were found. These were germinating, and most likely had come from some tree growing on a nearby hillside. Had a suitable soil been present, it seemed possible for some of the Sycamore seeds to have taken root and flourished. So also was it with other trees which grow in places where they are not usually expected to occur; that lists have been prepared of the vegetation found on Colonne Cathedral, the Coliseum at Rome, and for many other places. + +**How Seeds are Distributed.**—Seeds may be distributed in many ways— +(1) The seeds or fruits may be scattered by the wind. +(2) The seeds may be scattered by the fruit exploding, and so send individuals for a considerable distance from the parent tree. + +A diagram showing how seeds may be distributed. + +232 +BOTANY FOR BEGINNERS +CHAP. + +(1). The seeds or fruits may be scattered by clinging to the wood or hair of animals. +(2). The seeds and portions of the fruits may be scattered by animals swallowing them ; after passing through their bodies, the seeds are excreted. +Seeds Scattered by the Wind.—The seed or fruit often has wing-like appendages which make their superficial area greater than that of the body, so that they are blown about by the wind. When seeds or fruits of this kind are liberated from the parent plant, they fall slowly through the air, not straight down, but in zigzag lines, like the movements of a rook or lapwing, through the air. +The pappus of hairs which is produced from the calyx of the Dandelion aids in the dispersal of the fruit. In the Poppy and Larkspur, and in many other plants, the wind blows the fruit from side to side; the seeds are gradually distributed far from the parent plant. The following table shows the number of common seeds and fruits are scattered by the wind + +1. The fruits of the Ash, Sycamore, Elm, and birch, have appendages which carry them for a long distance from the parent plant. + +Fig. 230.--Fruit of Dandelion. +Fig. 230.--Ripe fruit of Sycamore. + +2. The fruits of the Dandelion, and most Composite possess a pappus of hairs, and are in this way carried through the air by the wind. + +XVII MORPHOLOGY OF SEEDS AND FRUIT 233 + +3. The seeds of the Willow, Poplar, and Willow-herb, have tufts of hair, which act like the pappus of the Dandelion. + +4. The seeds may be winged, as in the Begonia. + +5. The seeds may be small or flattened in form, as in the Ochilis, and are scattered by the wind when they are scattered by the wind blowing them out of the fruits. + +**Seeds Scattered by Explosive Fruits—Explosive fruits are those in which the seeds are ejected from their action. In the Box, the seeds are smooth, and are discharged by the pericarp contracting and forcing the seeds out like** + +Fig. 231.—Violet, F., explosive fruit; S., seeds being shot out of fruit. +Fig. 232.—Wood Sorrel, F., ding-dong fruit; S., seeds being shot out of fruit. + +A bean shot from between the fingers. The capsule of the Violet splits open, and, as the valves dry, they contract and fly out from the fruit. In the Wood-Sorrel and Squawking Cucumber, the fruit debouches with a loud noise, and flies off at a considerable distance. + +**Seeds Scattered by Clinging to Animals—Plants may produce fruits, and in a few rare cases seeds which are armed with hooks, by which the seeds adhere to the fur or wool of animals. A most familiar example is the Gallium, which grows in many of the hedgerows in the country lanes through-out the United Kingdom. Fracts which are armed with hooks** + +234 + +234 +BOTANY FOR BEGINNERS +CHAP. + +receive the name of *Avena*. The hooked fruit of the Wood Avens clings to animals, and is carried for great distances. A country walk through a district where these plants grow will best show how the fruits are distrib- +uted by animals. + +**Seeds Scattered by Animals.** The seeds are dispersed by passing through the alimentary canal of animals, they must possess certain characters which may be protected by a hard portion of the fruit, which is not acted upon by the digestive juices, or by the passage of the fruit through the alimentary canal. (f) The hard part of the fruit is often so large that it is not eatable to tempt the animal to swallow it. The droops of the Cherry, Blackberry, and Rambler Rose, are thus adapted for enticing the animal and afterwards drop- +ping the seed. As a rule, plants which produce fruits that are adapted for distribution by animals have succulent fruits, as the Apple, Strawberry, Rose-hips, and Currant. + +**Germination of Seeds.** The conditions necessary for the germination of seeds vary with different species. (g) That seeds have their vital functions arrested by drying is familiar to everyone; but when seeds are placed under suitable conditions of moisture and temperature, they can be found to find a permanent lodgment in the soil by the structure of their surfaces. Thus, the fruits of the Geranium and Grasses are enclosed in a hard coat, which resists changes in moisture which are produced by changes in the amount of moisture they contain. The 1vye-leaved Teasels, or Mother of Thousands, buries its seed capsules in the crevices of walls and cliffs. Nuts, Acorns, and other fruits are eaten by animals, such as the squirrel, and forgotten. Afterwards they may germinate. Some seeds have mucilaginous coverings, which not only fix them to the soil but absorb water. + +XVII MORPHOLOGY OF SEEDS AND FRUIT 235 + +Expt. 201.—Place some seeds of the Pumpkin on damp sawdust, and examine them from time to time. Note: + +(i) The seed-coat is thin and transparent, possesses a thickened base. At one end the hilum and micropyle occur. Split open the cotyledons; observe it is in an exalbuminous seed. + +(ii) The embryo (which grows from the micropyle) grows downwards and fixes itself in the soil. + +(iii) The radicle (the root) grows up, or peg or projection on the lower side which pins down the seed-cotyles while the cotyledons are extracted. + +(iv) The shoot (the stem) grows upwards, is curved, arched; this enables it to lift the soil far better than if it came up straight. + +(v) The cotyledons increase in size, open out, and perform the work of assimilation. + +Expt. 202.—Compare plants in various stages of germination. Note: + +(i) The embryo swells and bursts the testa. + +(ii) The radicle grows downwards and curves downwards and enters the soil. + +(iii) The hypocotylous stem, or portion beneath the cotyledons, comes up curved. + +(iv) The cotyledons are green even beneath the ground. They elongate and spread when exposed to light. + +(v) The phaneral develops and produces the foliage leaves. + +SUMMARY + +Changes in the embryo-sac form the endosperm, and convert the ovule into a seed. Seeds may be albuminous, i.e., have endosperm and embryo-sac, or scurpy, i.e., have no endosperm but only the embryo in the embryo-case. + +The scurpy is characterized with a testa which encloses the embryo and also the endosperm if it is present. + +The scurpy arises from some part of the ovule. + +Fruits are divided into true fruits and spurious fruits. A true fruit is formed by one ovule. A spurious fruit is formed by some other portion of the flower taken part in its formation. Some fruits of fruit is called the pericarp, which can be divided into epicarp, mesocarp, and endocarp. The epicarp is that which covers or protects the seeds, or they may not be durable. + +Fruits may be succulent or dry, and can be arranged into— + +** Succulent** Dry + +The drupe. +The nut. +The ilequa. + +The berry. +The achene. +The legume. + +The druplets. +The sarcarpus. +The follicle. + +236 +ROTARY FOR BEGINNERS +CH. XVII + +**Seeds may be distributed** by the wind; by explosive fruits; by clinging to animals; by the digestive process of animals. +Fruits or seeds may have appendages which act the part of a pas- +senger, such as the winged fruits of the fig, the seeds of the +wool of animals; or they may be mucilaginous and so get eaten by animals, thus being dispersed in their faeces. + +**Seeds germinate when placed under suitable conditions. Some** +plants have seeds which require moist earth with coverings which enable them to bore their way into the soil. + +**QUESTIONS ON CHAPTER XVII.** + +(1) Explain precisely in what points of structure a seed differs from an ovule. (1886.) + +(2) What is a fruit? How does a true fruit differ from a spurious fruit? (1886.) + +(3) What is a berry? What are the advantages to a plant to have this +kind of fruit? (1886.) + +(4) Describe and compare the fruits of the following plants—the +mango, the apple, the fig, the plum, the peach, the strawberry, the +blackberry, the raspberry, and the gooseberry. (1895.) + +(5) Draw and describe the fruit of a field Geranium, and point out the uses of some of its peculiarities. (1895.) + +(6) Describe and draw the seed of the Buttercup, of the Apple, and of the Onion. (1901.) + +(7) Describe and draw all allogamous and exogamous seeds, giving an example of each. What is the use of the allogamy? (1895.) + +(8) Describe and draw all autogamous seeds, giving an example of each. What is the use of autogamy? (1895.) + +(9) Describe and draw all heteromorphic seeds, giving an example of each. What is the use of heteromorphism? (1895.) + +(10) Describe and draw all homomorphic seeds, giving an example of each. What is the use of homomorphism? (1895.) + +(11) Describe and draw all heterocarpous fruits, giving an example of each. What is the use of heterocarpous fruits? (1895.) + +(12) Describe and draw all homocarpous fruits, giving an example of each. What is the use of homocarpous fruits? (1895.) + +(13) Describe and draw all syncarpous fruits, giving an example of each. What is the use of syncarpous fruits? (1895.) + +(14) Describe and draw all monospermous fruits, giving an example of each. What is the use of monospermous fruits? (1895.) + +(15) Describe and draw all polyspermous fruits, giving an example of each. What is the use of polyspermous fruits? (1895.) + +(16) Describe and draw all monoecious plants, giving an example of each. What is the use of monoecious plants? (1895.) + +(17) Describe and draw all dioecious plants, giving an example of each. What is the use of dioecious plants? (1895.) + +(18) Describe and draw all hermaphrodite plants, giving an example of each. What is the use of hermaphrodite plants? (1895.) + +(19) Describe and draw all self-fertilising plants, giving an example of each. What is the use of self-fertilising plants? (1895.) + +(20) Describe and draw all cross-fertilising plants, giving an example of each. What is the use of cross-fertilising plants? (1895.) + +CHAPTER XVIII + +THE PHYSIOLOGY OF REPRODUCTION + +Necessity for Reproduction - Hitherto the means by which plants maintain their individual lives have alone been considered. The limited duration of the life of a single plant is known to be due to its inability to reproduce itself by slugs, but larger animals also use them for food, and countless insects eat them too, live on them. Plants also struggle among themselves for food and light. Extremes of cold and heat have to be con- +tended with, and the whole organism must be kept in a constant state of change. + +Given this fact that plants die, the subject of reproduction becomes of vital interest, because it is not only ways—as far as is known—by which they can perpetuate themselves. All existing plants are the descendants of ancestral forms. + +By reproduction is meant the production of new individuals by natural means. There are two methods of reproduction: (1) By a portion of the vegetative part of a plant being cut off, from the parent plant, thus forming a new individual. This method is equivalent to the division of cells by mitosis (see p. 305). (2) By the union of two cells, one the male, the other the female. These cells, by their fusion, form a single cell which is capable of development into a complete plant. This method of reproduction is called sexual reproduction. + +Vegetative Reproduction - Any form of reproduction is comparatively rare in plants. Most any plant may be made separated into a form to produce a new individual. The branches of the Gooseberry bend down, and roots are formed at the ends of these branches, thus producing new plants from the parent plants. The runner of the Strawberry creeps over the surface of the soil for a considerable distance, and roots develop at its + +A diagram showing the process of vegetative reproduction in plants. + +nodes. This ultimately forms an independent individual by the interposing portion dying away. The off-set of the House-leek becomes similarly detached, and forms a new plant. The stolon of the Couch Grass performs the same function. In the axil of a leaf of the Caltha, a tuberous root is formed, which gradually exhausts the whole bulb, and carries on the life of the Plant. The Potato produces tubers at the ends of the stolons. These are detached, and form new plants. + +The Filewort and some of the Lilies produce small bulbs, which receive the name of bulbils, in the axil of leaves. These bulbils are capable of producing new plants, but do not require a parent plant to produce new individuals. The leaves of the Begonia and other plants will, if they come in contact with the soil, produce new plants. + +The Biological Importance of Vegetative Reproduction.--As long as the food supply is plentiful, and the surroundings are favourable, vegetative reproduction suffices. It is an easy way of increasing the number of the population. Most plants in which it is possible. Gardeners use this method on a large scale for the production of any favourable character which a plant may possess. But when food is scarce, or when conditions are indulged in for a long time by a particular race of plants there is a tendency for the race to degenerate. Most plants, however, also reproduce their kind by organs which are produced in a sexual manner. + +Sexual Reproduction.--The male reproductive cell is the generative nucleus, or spermatozoon, which enters into the oosphere in the embryo-sac. The former is called the male pronucleus, and the latter the female pronucleus. Neither of these cells can exist independently; only when they unite does a reproductive cell be formed by their union. The union of the male cell with the female cell stimulates the cell formed, and it develops into an individual which combines the good or bad characters of the parents. The offspring thus derived from vegetative reproduction in the fact of cells, which produce the new plant, being formed in special organs--the pollen grain and embryo-sac--it follows that in a single cell there should be stored up the potentiality of the future plant, or in other words, a single cell should be able to produce a perfect plant. + +28 +BOTANY FOR BEGINNERS +CHAP. +A page from a book about botany for beginners. + +XVIII THE PHYSIOLOGY OF REPRODUCTION 239 + +The Biological Importance of Sexual Reproduction. +—The biological importance of sexual reproduction cannot be overestimated. As long as the surroundings of a plant are favourable, vegetative reproduction suffices to maintain the community. The reproductive life of the particular race of plants can only be continued over the hard time by sexually produced bodies. The seed produced as the result of sexual union is capable of retaining its vitality during a long period, even when the parent plant has perished, until the mature plant. During a period of drought the vitality of the young embryo within the seed is only suspended, not de- +stroyed. When conditions become again suitable, these con- +ditions recur again, it germinates and produces new plants. +Life-History.—All the changes which a plant undergoes before death are called its life-history. The life-history of a perennial plant consists of the germination of the seed, the production of leaves, the growth to maturity, when either flowers and produces pollen grains or seeds, or both, or the generative nucleus of the pollen grain unites with the oosphere in the ovule, and the oospore is formed. The oospore develops into the embryo, and a seed is produced. The parent dies, but the particular race of plants is carried on by the embryo in the seed. + +The life-history of an annual plant consists of the germination of the seed and the production of the seedling; its growth and the storing up of reserve material, which ends first the first year of its life; then during the second year growth recommences, and flowers are produced, and pollen grains and ovaules are formed; these produce seeds, and the parent dies too. + +The life-history of a perennial plant takes three or more years for its completion. It consists of the germination of the + +Fig. 534.—Graphic illustration of the Lifehistory of an annual plant. + +240 +BOTANY FOR BEGINNERS +CHAP. + +seed, the production of the seedling, and its growth until maturity is reached. Flowering then takes place, once or many times, and seeds are formed. The plant may only live a few years, or for a thousand years. It is shown in Fig. 235 that trees with several hundred rings, which mark so many years of growth, and the trunk of Sequoia in the British Museum has 1330 annual rings. The life-history of a plant is shown in a graphic manner in Fig. 236. + +SUMMARY. +The Necessity for Reproduction is shown by the fact that plants are produced by means of seeds, which are the means by which new individuals can be produced by sexual reproduction. + +Vegetative Reproduction is a plant taken by a part or a whole of another plant of the same kind, and grown into an independent life as a new individual. + +The Sexual Reproduction of a plant is brought about by the union of two individuals, these being their progenitors, and one of them produces the embryo. + +The Biological Importance of Reproduction is shown by the increase in number of the individual, and by the better chance it gives the offspring by the distribution of the seeds far away from the parent. The seeds produce great numbers of individuals, and thus perpetuate themselves. + +The Life-History of a plant consists of all the changes which it undergoes from birth to death. + +Fig. 235.—Graphic illustration of the Life-history of a plant. + +Fig. 236.—Graphic illustration of the Life-history of a plant. + +XVIII THE PHYSIOLOGY OF REPRODUCTION 541 + +QUESTIONS ON CHAPTER XVIII. + +(1) Give an account of the different ways in which plants propagate themselves otherwise than by seed. (1893.) + +(2) Why is reproduction necessary in plants? Enumerate the two ways in which it is effected in plants. + +(3) Define what is meant by "sexual reproduction." How does it take place? + +(4) What is the biological importance of sexual reproduction? + +(5) Explain the difference between sexual and asexual reproduction. + +(6) Trace the history of an annual plant from the time of the germination of its seed to the time when it has produced seeds of its own. + +(7) How does the life-history of an annual plant differ from the life-history of a perennial plant? + +(8) Show in a graphic manner the life-history of— + +(a) An animal plant. +(b) A flowering plant. +(c) A perennial plant. + +A. A common feature amongst organisms is that they all have a definite period during which they are capable of producing offspring. This period is called their reproductive period. The length of this period varies with different species. In some cases it may be very short, as in the case of insects, while in other cases it may be very long, as in the case of mammals. In general, however, the reproductive period is longer in animals than in plants. + +B. The reproductive organs of animals are usually located on the surface of the body, while those of plants are usually located within the body. In animals, the reproductive organs are often modified to form special structures, such as the penis and vagina. In plants, the reproductive organs are usually located within the body, and are often modified to form special structures, such as the stamens and pistils. + +C. The reproductive organs of animals are usually located on the surface of the body, while those of plants are usually located within the body. In animals, the reproductive organs are often modified to form special structures, such as the penis and vagina. In plants, the reproductive organs are usually located within the body, and are often modified to form special structures, such as the stamens and pistils. + +D. The reproductive organs of animals are usually located on the surface of the body, while those of plants are usually located within the body. In animals, the reproductive organs are often modified to form special structures, such as the penis and vagina. In plants, the reproductive organs are usually located within the body, and are often modified to form special structures, such as the stamens and pistils. + +E. The reproductive organs of animals are usually located on the surface of the body, while those of plants are usually located within the body. In animals, the reproductive organs are often modified to form special structures, such as the penis and vagina. In plants, the reproductive organs are usually located within the body, and are often modified to form special structures, such as the stamens and pistils. + +F. The reproductive organs of animals are usually located on the surface of the body, while those of plants are usually located within the body. In animals, the reproductive organs are often modified to form special structures, such as the penis and vagina. In plants, the reproductive organs are usually located within the body, and are often modified to form special structures, such as the stamens and pistils. + +G. The reproductive organs of animals are usually located on the surface of the body, while those of plants are usually located within the body. In animals, the reproductive organs are often modified to form special structures, such as the penis and vagina. In plants, the reproductive organs are usually located within the body, and are often modified to form special structures, such as the stamens and pistils. + +H. The reproductive organs of animals are usually located on the surface of the body, while those of plants are usually located within the body. In animals, the reproductive organs are often modified to form special structures, such as the penis and vagina. In plants, the reproductive organs are usually located within the body, and are often modified to form special structures, such as the stamens and pistils. + +I. The reproductive organs of animals are usually located on the surface of + +CHAPTER XIX + +THE CLASSIFICATION OF PLANTS + +Natural System.--The natural system of botanical classifica- +tion is based on the resemblances and differences in plants, on +the structure, in fact, of both their vegetative and reproductive organs. The classification of the plants is divided into two +sub-kingdoms (i) Phanerogama, and (ii) Cryptogama. All +plants belonging to the former division produce flowers and +seeds, while those belonging to the latter division do not pro- +duce seeds. The Phanerogama are again divided into (a) Angio- + sperma and (b) Gymnosperma. The Angiosperms have +their ovules enclosed in a fruit, while the Gymnosperms have +naked ovules. The Angiosperms include two main classes (c) +Dicotyledona, and (d) Monocotyledona. + +Dicotyledons plants have the +diverging leaves opposite each other. +The seedling possesses no radicle. +The foliage leaves are pinnate. +The vascular bundles are arranged in two rows and are +arranged form a circle around the stem. +The parts of the flowers occur either in five, fourrs, or multiples of this number. + +Divisions of Dicotyledona.--The dicotyledons plants can be arranged into four sub-clases, according to the structure +and arrangement of their floral whorls. + +1.--Thalassifera.--All dicotyledon plants which have +the stamens 4-2-2 (p. 183), and the pistil superior (p. 183). + +CH. XIX THE CLASSIFICATION OF PLANTS 243 + +(2) Caryophyllaceae—All dicotyledonous plants which have the stamens perigynous (p. 87) or epigynous, and the pistil either superior or inferior. + +(3) Gomphostemaceae—All dicotyledonous plants with gomphostemous stamens and epigynous or hypogynous pistils, the pistil either superior or inferior. + +(4) Incompleteae—All dicotyledonous plants with the corolla divided into two lips. + +Divisions of Monocotyledones—the monocotyledons are arranged into three sub-classes, according to the structure and arrangement of their floral organs. + +(1) Petaloideae—All monocotyledonous plants with coloured flowers. + +(2) Spadiceae—All monocotyledonous plants with the flowers enclosed in a spathe. + +(3) Glumaceae—All monocotyledonous plants with the flowers enclosed in a glume. + +Each of these sub-classes into which the dicotyledons and monocotyledons are divided includes a number of orders, and each order consists of a number of familiar plants which are closely related. These are dealt with in this chapter are shown below in a tabular form. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
Natural Order.
Distinguishing Characteristics.
(a) RanunculaceaeStamens indefinite (p. 185), hypogynous, (p. 186).1stilium sparsocarpus (p. 186).
(b) CruciferaeSepals and petals in the form of a cross.2ndilium sparsocarpus (p. 186).
(c) Caryophyllaceae1stilium sparsocarpus (p. 186), carpel z.3rdilium sparsocarpus (p. 186).
Lowers, opposite and entire; nodes swollen.4thilium sparsocarpus.
Stamens 3 to 2 series.R
+ +344 +BOTANY FOR BEGINNERS +CHAP. + +Sub-Class . . . . . Calyciferae + +Natural Order. +Distinguishing Characteristics. + +(a) Leguminosae . . . . (i) Flowers syngamous (p. 179). +(ii) Stamens alternate, filiform, filiformulous or dia- +phorous (p. 185). +(b) Rosaceae . . . . (iii) Flowers actinomorphic (p. 179). +(iv) Stamens indefinite, perigynous (p. 185). +(v) Filist syncarpous, carpel 2 ; ovary unisexual +or bisexual (p. 186). +(c) Umbelliferae . . . . (vi) Stamens in compound umbels (p. 168). +(vii) Stamens epigynous (p. 185). +(viii) Filist. +Sub-Class . . . . Gamopetalum + +Natural Order. +Distinguishing Characteristics. + +(a) Compositae . . . . (i) Flowers in heads. +(ii) Filist syncarpous, carpel 2 ; ovary one- +celled (p. 185). +(5) Primulaceae . . . . (iii) Flowers actinomorphic. +(iv) Stamens 4, opposite to corolla lobes. +(v) Filist syncarpous, free central (p. 187). +(b) Boraginaceae . . . . (vi) Leaves entire and hairy. +(vii) Stamens 4, alternant with corolla lobes. +(viii) Stamens 5, alternating with corolla lobes. +(ix) Filist syncarpous, carpel 2 ; ovary four- +celled (p. 187). +(d) Scrophulariaceae. . . (x) Stem round. +(xi) Flowers zygomorphic. +(xii) Stamens diaphanous (p. 185). +(xiii) Filist syncarpous, carpel 2 ; ovary two- +celled (p. 187). +(xiv) Filist syncarpous, carpel 2 ; ovary four- +lobed and four-celled, with one ovule in each cell. +(xv) Labiatae . . . . (xiv) Flowers two-lipped, zygomorphic. +(xvii) Stamens epigynous (p. 185). + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
XIX THE CLASSIFICATION OF PLANTS
245
Sub-Class . . . . Incomplete.
Natural Order. Distinguishing Characteristics.
(a) Cupulifera - . . .(i) Male flowers in catkins.(ii) Female flowers sessile in an involucre of bracts.
Sub-Kindred PHANEROCAMPS. ANGIOSPERMS.
Division . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Corylus - Potentilla - Aesculus - Petasites.
Natural Order. Distinguishing Characteristics.
(a) Liliaceae -(i) Perennial either gamophytes or polyphytes;(ii) Ovary superior; ovules axile placentaion.
(b) Amaryllidaceae -
(i) Perennial generally with a corona (p. 281).
(ii) Ovary inferior.
+ +**Meaning of a Natural Order.**—A natural order is built up of genera which have a common origin and certain characters. The genus in its turn includes several plants resembling each other in one or more respects. The narrowest systematic arrangement is that of the genus to the species, but this is closely related that they must have descended from a common ancestor. + +**Naming of Plants.—Each plant receives two scientific names; the first indicates the genus, the second the species. Thus, for instance, the Termentil, Potentilla termentilis, and the side-wood, Potentilla anserina, are two species of the genus Potentilla. + +The following scheme indicates how each plant is arranged in its true position in the natural system of classification : + + + + + + + + + + + +
Sub-KindredKindredClassOrderNatural OrderGenus -Species
PHANEROCAMPS.ANGIOSPERMS.Corylus - Potentilla - Aesculus - Petasites.
DIOTYLEDONIUM.
Rosaceae.
Potentilla.Termentil or Anserina.
+ +246 +BOTANY FOR BEGINNERS +CHAP. + +DESCRIPTION OF NATURAL ORDERS. +Sub-Kingdoms: PHANEROGAMS, ANGIOSPERMS, DECOTYLEDONS. +Divisions: ANGIOSPERMS, DECOTYLEDONS. +Clas: ANGIOSPERMS, DECOTYLEDONS. +Sub-Clas: ANGIOSPERMS, DECOTYLEDONS. + +Natural Order: Ranunculaceae (Buttercup Family).— +The plants belonging to this natural order are usually medium- +sized herbs. The leaves are radical or cauline ; if the latter they are alternate, simple, entire, and deciduous. The flowers are regular ; the stamens are indefinite and hypogynous. The pistil is apocarpous. The fruits consist of one-seeded achenes (p. 228), or many seeded follicles (p. 230). + +Floral formula.—K:5 C:5 A:0 G:1 to 6. +Description of a Typical Buttercup (Ranunculus Auriz). +**Habit.—A hairy perennial plant with erect stem and straight rootstock. It grows in meadows, and flowers from April to September.** + +Fig. 327.—Hypogynous flower of Ranunculus, with numerous superior carpels on the receptacle. (Magnified.) (3.) + +Root.—A branched tap-root. +Stem.—Straight or ascending, round, hollow, hairy, green. +Leaves.—Both radical and cauline ; cauline leaves alternate, simple ; lower leaves deeply divided ; upper, narrow and not divided ; uppermost developed sheath present, reticulate-veined, hairy, exstipulate. + +Inflorescence.—Definite ; the axis ends in a flower. + +Flowers.—Complete ; acuminatiform, about three-quarters of an inch in diameter, yellow. + +A diagram showing the structure of a flower from the Ranunculaceae family. + +XIX THE CLASSIFICATION OF PLANTS 347 + +Calyx.—Polyvalvate, 5, inferior, hairy, green. +Corolla.—Polyvalvate, 5, hypogynous, each petal with a nectary at base. +Androecium.—Free, indefinite, hypogynous ; filament long ; anther two-lobed and basifused. + +A branch with flowers : B, longitudinal sec- +tion of flower ; C, flower from below ; D, petal ; +E, stamen ; Ca, carpel. One-chord (nat. size). +Fig. xyl.—Rutaceae (Rutaceae). + +Gynaeceum.—Apocarpous ; carpels numerous, spirally arranged on a conical receptacle ; sepals persistent. +Fruits.—Achenes with a single seed in each ; seeds possess +endosperm. + +Pollination.—The outer stamens ripen first, then the inner ones. The carpels ripen between the two sets of stamens. In this way either self-pollination or cross-pollination can take place. The flowers are visited by insects of different kinds to flower and pollen, and these, creeping over the flowers, may either bring pollen from another flower, and so cross-pollinate ; or + +248 +BOTANY FOR BEGINNERS +CHA. +they may distribute the pollen from the stamens to the pistil of the same flower and produce self-pollination. + +EXCEPTIONS TO THE ABOVE TYPE. +Moenkohsch (Acmonium napellus).—Flowers 5 racemes, zygomorphic; Calyx 5, sepals 3, sepals 2, petals 3; sepals modified to form long-keeled neotestis; the other 6 may be absent or present as a rudiment. Carpel 3; ovules numerous. Prostomous : Fructif. many- +branous ; seeds numerous, covered by bulbous-hemispheres, +covered by bulbous-hemispheres. +Sepals petaloid ; Petals 8 ; stamens 8 ; pistil 1 ; flowers +harbored, modified to form nec- +testis, which is pollinated by insects ; +limited by insects ; H. Niger is the Christmas +Tree. +Anemone (Anemone me- +nziesii).—Flowers 5 ; petals +abscissed ; stamens (petaloids) +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent ; Pollinated by insects. +Sepals petaloid ; Petals 5 ; +sepals 2, petals 3 ; stamens +abscissed ; pistil (petaloid) ab- +sent : Pollinated by insects. +Sepals petaloid; Petals +5; sepals 2, petals + +The rootstock is from two to three inches in length, and ends in a point. + +If it is cut and consumed, and pos- +sesses no poison substance. + +If scraped when fresh it turns yellow. + +The root of Acmonium is largely used in medicine. + +XIX +THE CLASSIFICATION OF PLANTS +249 + +**Ranunculus.**—All species are more or less poisonous. The Celery-leaved Crowfoot is probably most poisonous. *R. ariet* frequently causes poisoning in cattle. The Marsh Marigold is a source of danger to horses and dogs. + +All species of *Anemone* and *Helleborus* are poisonous. + + +A circular diagram with a central circle and two concentric outer circles. The innermost circle has a single large dot in its center. The second circle contains three smaller dots arranged in a triangular formation. The outermost circle contains four smaller dots arranged in a square formation. + + +Fig. 240.—Menzoberr (Acacia). (One-third nat.) +(die.) (S. G.) + + +A circular diagram with a central circle and two concentric outer circles. The innermost circle has a single large dot in its center. The second circle contains three smaller dots arranged in a triangular formation. The outermost circle contains four smaller dots arranged in a square formation. + + +Fig. 241.—Floral diagram of *Ceratophyllum*. + +**Natural Order:** Cruciferae. —(Wallflower Family). The plants of this order have either radical or cauline leaves, which are exstipulate. The flowers are in racemes and are cruciform. See also *Brassicaceae*. Stamens 6, tetradynamous. Pistil syncarpous, carpels 2. Ovary two-celled. Ovules numerous, parietal placentation. Fruit either a capsule or a silique. + +NOTE.—This is the only order with tetradynamous stamens. + +Floral formula.—K+2, C4, A+4,G(2). + +--- +**Note on the Classification of Plants** + +The classification of plants presented here follows the system proposed by the British Botanical Society in 1875, which was based on the work of Carl Linnaeus (1707-1778) and his successors. This system was revised and updated by the International Botanical Congress in 1953, and again in 1969. + +The classification presented here is based on the following orders: + +1. **Monocotyledons** + - **Liliopsida** + - **Zingiberales** + - **Zingiberaceae** + - **Zingiber** + - **Orchidales** + - **Orchidaceae** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orchis** + - **Orach** + +250 +BOTANY FOR BEGINNERS +CHAP. + +Description of a typical Crucifer. *Chieranthus* +*Chier.*—(Wallflower). +**Habit.**—A perennial plant which grows on old walls, and is largely cultivated in gardens. +**Root.**—A much branched, woody tap-root. + +A flower with five petals, three of which are longer than the other two. +A long, narrow leaf. +A long, narrow leaf. +A long, narrow leaf. + +Fig. 345.—Wallflower (*Chieranthus*). A, Branch and inflorescence; B, flower; C, longitudinal section of flower; D, stamens and pistil; E, fruits; S, transverse section of stem. + +Size.—Woody below and herbaceous above; leaves, branched, ribbed; the lower part is covered with pale brown bark, and the upper portion is coloured green and is hairy. +*Leaves.**—Cauline, alternate, sessile, lanceolate, acute, entire and reticulate-veined. Upper side dark green and slightly hairy ; the lower side pale green and more hairy : stipulate. + +A flower with five petals, three of which are longer than the other two. +A long, narrow leaf. +A long, narrow leaf. +A long, narrow leaf. + +XIX +THE CLASSIFICATION OF PLANTS +251 + +*Inferioriens*—Indifferent, erect, raceme. +*Flowers*—Complete, actinomorphic, cruciform. Diameter 1½ inches. Yellow or reddish-brown in colour and sweet scented. +*Calyx*—Polysepalous; 2-4, inferior; inner sepals saccate ; outer 3-6, free. +*Corolla*—Polypetalous ; petals 4, hypogynous and clawed. +*Androecium*—Free ; stamens 6, tetradynamous, hypogynous ; front stamens with filaments united at base. +*Gynaeum*—Symparous ; carpels 2 ; ovary superior, linear, spuriously two-celled ; style short ; stigma 2-fid. +*Ovary*—Subglobose. +*Fruit*—A silique. Seeds with a little endosperm. +*Pollination.* The flowers are visited by insects for their honey, which is stored in the saccate sepals. + + +a b c d e f g h i j k l m n o p q r s t u v w x y z + + +Fig. 318.—Wild Radish (Raphanus sativus). *a*, flower (first stage); *b*, petal ; *c*, pro- +dorium and gynoecium ; *d*, pod with glands; *e*, fruit ; *f*, transverse section of fruit ; +*g*, longitudinal section of fruit. +252 + +**Properties of Cruciferae.** All Cruciferae are wholesome, being largely used for food. Many are valuable because of the organic acids they contain. + +The principal plants of this order cultivated for food are : (a) For their roots, Turnip (Brassica campestris). (d) For their leaves, Cabbage (Brassica oleracea), Kales (Brassica rapa), Mustard (Brassica juncea), and other plants bearing large axillary buds. The young seedlings of the Cress (Lepidium sat. + +253 + +252 +BOTANY FOR BEGINNERS +CHAP. + +cowo, and the White Mustard (B. alba) are used for salad. (c) For their +influences—Cauliflower and Broccoli are varieties of Cabbage. Their influences are benedict and very succulent. The flowers are very much like those of the cabbage, but they are smaller, and of which the mustard of commerce is produced. (d) For their oil, Rapeseed and Colza Oil are used. (e) For their roots, Carrot and Turnip are used. +Natural Order: Caropylum, (Stitchwort family.) +The plants belonging to this order have swollen nodes, opposite leaves, and flowers with five sepals, two petals, and three stamens, or dichotomous cymose. The calyx consists of five united or free sepals. The corolla is made up of five petals, each deeply cut or entire. There are two styles, one superior, the other inferior, ripen five at a time. The pistil is syncarpous, the carpels varying in number from 3 to 5. The placentaion of the ovules is axile. +From these facts it will be seen that these plants are pro- +tandrous and pollinated by insects. +NOTE.—No other order possesses the characteristics of this group except the Cruciferae. See page 106. +site entire leaves, and to free stamens in two series. +Fig., 244.—Floral diagram. +Description of a typical Caropylum phyllaceous Plant (Stellaria media). +Stitchwort. +Habit.—An annual or perennial plant with many branches, which grows nearly everywhere. +Root.—Short, and very slender. +Stem.—Swollen at the nodes, very hairy, herbageous and green. +Leaves.—Capitula, open or complete, entire, narrow. Lower +leaves often hairy; while the upper are sessile; exstipulate. +Inflorescence.—Definite, forming dichotomous cymes. +Flowers.—Complete, actinomorphic, stellate, small, white. +Calyx.—Petaloid; 5 sepals; 5 lobes; 5 lobes. +Corolla.—Polypetalous; 5 hypogynous, petals split. +Androecium.—Free ; 10 stamens in two series ; hypogynous ; +the outer ones sterile; the inner ones fertile; while the others +alternate with them ; filaments slender ; anther two-lobe. +Gynaeicum.—Symparous ; carpels 5 ; superior ; styles 3 ; +stigmas 3. + +Fig. 244.—Floral diagram. + +XIX +THE CLASSIFICATION OF PLANTS +253 + +*Ovary.*—One-celled; ovules axile placentation. +*Fruits.*—A capsule which opens by valves. Seeds with perisperm. +*Pollination.*—Honey is produced in five nectaries, forming small knobs outside the stamens. The flowers are cross-poll. + + +A B C D E F + + +Fig. 841.—Scheuchzeria (Scheuchzeria). A, branch, with inflorescence; B, longitudinal section of flower; C, corolla as seen from above; D, petal; E, summer; F, plant. (The fourth tab. size.) +
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+br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br +br + +Properties.—A few plants of this order possess poisonous properties. The most dangerous plant is *Lysimachia thyrsiflora*, the Core Cockle, which grows in cardinals. Its leaves are very narrow, flowers violet- + +254 +BOTANY FOR BEGINNERS +CHAP. + +coloured, and the seeds are produced in capsules. It is harvested along with the corn, and is separated from it by machinery. If the flour should contain large quantities of the seeds of this plant bad results may follow from the consumption of it. The plant is a native of South America, but is now grown extensively in the United States. It is a stunted perennial plant with rose-coloured flowers. All parts of this plant possess a poisonous substance. + +A branch of Campsis, B, a separate flower; C, longitudinal section of flower; D, flower seen from above. + +Sub-Class: Calyciflora. +Natural Order: Leguminosae (Pea Family).—The plants belonging to this natural order may be either herbs, shrubs, or trees. The leaves are alternate, being usually compound and stipulate. The flowers are syngomorphic and papilionaceous. The calyx + +Fig. 176.—A, branch of Campsis; B, a separate flower; C, longitudinal section of flower; D, flower seen from above. + +XIX THE CLASSIFICATION OF PLANTS 255 + +is gamopetalous. The corolla is polypetalous and consists of a standard, wings, and keel. The ten stamens are either dia- +dolphous or monadelphous. The pistil is monocarpous. The fruit is a legume while the seeds are elatineous. +*Pisum sativum*, L. (3), Aq.+1 or (1a). G1. +Description of a type plant of the Leguminosae.--- +(Pisum Sativum, Garden Pea). + + +A: A single flower with five petals. +B: Another single flower showing the same structure. +C: A side view of a flower showing the stamens and pistil. +D: A close-up of the flower's base, showing the two petaloids forming the keel. +E: A different angle of the flower, showing the stamens and pistil more clearly. +F: A different angle of the flower, showing the stamens and pistil more clearly. +G: A different angle of the flower, showing the stamens and pistil more clearly. +H: A different angle of the flower, showing the stamens and pistil more clearly. +I: A different angle of the flower, showing the stamens and pistil more clearly. +J: A different angle of the flower, showing the stamens and pistil more clearly. +K: A different angle of the flower, showing the stamens and pistil more clearly. +L: A different angle of the flower, showing the stamens and pistil more clearly. +M: A different angle of the flower, showing the stamens and pistil more clearly. +N: A different angle of the flower, showing the stamens and pistil more clearly. +O: A different angle of the flower, showing the stamens and pistil more clearly. +P: A different angle of the flower, showing the stamens and pistil more clearly. +Q: A different angle of the flower, showing the stamens and pistil more clearly. +R: A different angle of the flower, showing the stamens and pistil more clearly. +S: A different angle of the flower, showing the stamens and pistil more clearly. +T: A different angle of the flower, showing the stamens and pistil more clearly. +U: A different angle of the flower, showing the stamens and pistil more clearly. +V: A different angle of the flower, showing the stamens and pistil more clearly. +W: A different angle of the flower, showing the stamens and pistil more clearly. +X: A different angle of the flower, showing the stamens and pistil more clearly. +Y: A different angle of the flower, showing the stamens and pistil more clearly. +Z: A different angle of the flower, showing the stamens and pistil more clearly. +AA: A different angle of the flower, showing the stamens and pistil more clearly. +BB: A different angle of the flower, showing the stamens and pistil more clearly. +CC: A different angle of the flower, showing the stamens and pistil more clearly. +DD: A different angle of the flower, showing the stamens and pistil more clearly. +EE: A different angle of the flower, showing the stamens and pistil more clearly. +FF: A different angle of the flower, showing the stamens and pistil more clearly. +GG: A different angle of the flower, showing the stamens and pistil more clearly. +HH: A different angle of the flower, showing the stamens and pistil more clearly. +II: A different angle of the flower, showing the stamens and pistil more clearly. +JJ: A different angle of the flower, showing the stamens and pistil more clearly. +KK: A different angle of the flower, showing the stamens and pistil more clearly. +LL: A different angle of the flower, showing the stamens and pistil more clearly. +MM: A different angle of the flower, showing the stamens and pistil more clearly. +NN: A different angle of the flower, showing the stamens and pistil more clearly. +OO: A different angle of the flower, showing the stamens and pistil more clearly. +PP: A different angle of the flower, showing the stamens and pistil more clearly. +QQ: A different angle of the flower, showing the stamens and pistil more clearly. +RR: A different angle of the flower, showing the stamens and pistil more clearly. +SS: A different angle of the flower, showing the stamens and pistil more clearly. +TT: A different angle of the flower, showing the stamens and pistil more clearly. +UU: A different angle of the flower, showing the stamens and pistil more clearly. +VV: A different angle of the flower, showing the stamens and pistil more clearly. +WW: A different angle of the flower, showing the stamens and pistil more clearly. +XX: A different angle of the flower, showing +[Continue with other angles...] + + +**Fig. 247.—A leaf-flower of Pisum. B., a side view of flowers C., flowers from +the same plant. Longitudinal section D., shown ; 1., a petaloid ; 2., wing ; 3., two +petals which form keel.** + +**Habit.—A weak annual plant which climbs by means +of tendrils.** + +256 +BOTANY FOR BEGINNERS +CHAP. + +Root.—A branched tap-root with a large number of nodules on the branches. These nodules are caused by bacteria (p. 130). +Stem.—Herbaceous, ribbed, solid, hairy, green. +Leaves.—Cauline, alternate, pinnate compound, stipulate; the stipules deciduous, green, and persist; some of the leaflets are converted into tendrils. +Inflorescence.—Axillary and two-flowered. +Flowers.—Petals 5 ; sepals 5 ; stamens, papilionaceous ; diameter one inch; generally white in colour. +Calyx—Gamaeopalous ; 5 lobed ; perigynous ; green and hairy. +Corolla.—Polypetalous ; 5 petals ; perigynous ; consists of a standard, wings, and a keel (p. 180). +Androecium.—Diadelphous ; the stamens sessile ; perigynous ; the single gynoecium free and the rest united having an opening all along the posterior face as well as at the top of the bundle. At the base of the inner row of stamens five nec- +taries are inserted which hold them accumulations between the stamens and the base of the ovary. +Gynaeceum—Monocarpous ; superior ; parietal placentation. +Fructification.—Fruit a capsule. +Pollination.—The flowers of all the plants of this order are adapted for insect pollination. The pea is generally pollinated by the bee, which alights on the flower and rests on the edge of the flower as a platform; its weight pulls these down and draws the keel forward. The stamens, protected by the keel, thus come in contact with the stigma. The bee then thrusts its tongue down to the slit in the bundle of stamens and sucks up the honey. As flower after flower is visited, cross-pollination occurs. Self-pollination sometimes takes place. +Other Lepiduminae—Trifolium repens (Dutch Clover) is a creeping perennial. Each leaf is divided into three leaflets and at its base there is a petiole. The leaves are trifoliate. Cytisus (Luburnum and Broom) possesses monadelphous stamens. +Vicia faba (Bean) has a pod with a flat surface. Phaselia cucumer (Scurflet Runner) has a hand-bentvinging stem by means of which it climbs around slender supports. +Properties.—The leaves of all these plants are used in medicine; some are poisonous, others are largely cultivated for food. Luburnum.—The seeds of Luburnum are poisonous. The plant can + +XIX THE CLASSIFICATION OF PLANTS +237 + +be recognised by its ternate leaves, its racemes of large yellow flowers, and many seeded legumes. Most of the other plants belonging to the genus Cyrtisus are shrubs. + +**I. The Plants Cultivated for Food.** The following are the principal plants which are cultivated for food in the United Kingdom :— + +Cabbage—Brassica oleracea. +Beans—Phaseolus vulgaris. +Cherry—Prunus avium. +Medicaginæ—Medicago sativa. +Sainfoin—Onobrychis viciifolia. + +**II. The Plants Cultivated for Ornamental Purposes.** + +Bird's-foot Trefol—Lotus corniculatus. +Common Melilot—M. officinalis. +Furze, gorse, or whin—Cistus. + + +A diagram showing the structure of a flower. It includes a central disc (5) with several rays (6) radiating outwards, each ray having two petals (7). There are also three sepals (8), one petal (9), and a stamen (10). + + +Fig. 238.—Bird's-foot Trefol (Lotus corniculatus). + +1. Flowering branch ; 2, flower ; +3, petal ; 4, stamen ; 5, carpel ; 6, fruit ; 7, corolla ; 8, standard ; 9, wings ; 10, filament. + +Natural Order: Rosaceae (Rose Family)—The plants of this order are either herbs or woody plants. The leaves are generally alternate and stipulate. The flowers are actinomorphous and perigynous. The sepals and petals are usually four or five in number and the stamens are indefinite and perigynous. The pistil is either episcorophorous or monocarpous while the number + + +A diagram showing the structure of a flower. It includes a central disc (5) with several rays (6) radiating outwards, each ray having two petals (7). There are also three sepals (8), one petal (9), and a stamen (10). + + +Fig. 239.—Rose Family (Rosaceae). + +258 +BOTANY FOR BEGINNERS +CHAEL. + +of carpels varies from one to many. Fruit various. Seeds either with or without endosperm. +NOTE.—The difference between the plants of this order and those of the natural order Ranunculaceae consists in their perigynous stamens. + +Flower diagram of Rubus fruticosus. +Fig. 149.—Blackberry (Rubus fruticosus). 1, Flowering branch ; 2, longitudinal section of flower ; 3, fruit ; 4, floral diagram. (S.J.) + +Floral formula.—K(5), C(5), A(0), G (1 or 2). +Description of a typical plant of Rosaceae (Rosa canina, Desf.). + +Habit.—A prickly shrub with large coloured flowers. +Root.—A tap-root with woody branches. +Stem.—Woody, prickly, and covered with bark. + +Flower diagram of Rosa canina. +314 + +XIX THE CLASSIFICATION OF PLANTS + +259 + +**Leaves.—Cauline, alternate, pinnately compound, with a terminal leaflet. The margin of the leaf is serrate. Leaves are stipulate, and these are adnate (p. 46).** + +**Inflorescence.—Definite. The flower is produced at the end of a stalk (in some cases other flowers may be produced in subbracteal bracts).** + +**Bract.—Bracteate.** + +**Flower.—Simple, actinomorphic, large, coloured, and sweet-scented.** + + +A small illustration showing a flower with three petals and a central stamen. + + +Fig. 230.—Pear (Pyrus communis). 1, Flowering branch; 2, longitudinal section of flower bud; 3, flower; 4, stamens; 5, carpel; 6, ovule; 7, ovary; 8, calyx; 9, corolla. + + +**Calyx.—Gamosepalous, 5 lobed, sepals inferior.** + +**Corolla.—Polypetalous; 5 perigynous petals.** + +**Androecium.—Free, indefinite, perigynous stamens.** + +**Gynaeceum.—Apocarpous; carpels numerous and superior. Each carpel contains a single ovule.** +5 + +250 +BOTANY FOR BEGINNERS +CHA. +**Fruit.**—A pseudocarp concealing a number of achenes. Seeds have no endosperm. +**Pollination.**—By insects. + +EXCEPTIONS TO THE ABOVE TYPE. +The Order Rosaceae is a very large one, and contains a number of plants differing in some respects from the Dog Rose. + +**Star-Wood (Styrax)** +**Calyx.**—Under the calyx, and alternating with the sepals, a shoot, or phyllodium, is produced, which bears the petals in an *glaucy*, repre- +senting the stipules of the sepals joined together. + +**Prunus.**—The fruit is formed by the enlargement of the receptacle, which swell to form a cup-like cavity. The flat white, then red, sweet, and juicy flesh is surrounded by a hard, woody, compound receptacle bearing the persistent calyx. + +A diagram showing the structure of a fruit, possibly a cherry or plum. + +Fig. 231.—Cherry (Prunus cerasus). 1, Flowering branch ; 2, longitudinal section of flower-bud ; 3, longitudinal section of fruit. (S.) + +**Cherry. Plum and Apple** (Prunus) + +**Pedicel.**—The fruit is monocarpous ; after pollination the single carpel swells up and a one-seeded fruit is produced. This is a drupe which is a simple fruit. + +XIX +THE CLASSIFICATION OF PLANTS +263 + +Apple and Pear (Pyrus)�� + +**Fruit.—The fruit consists of five carpels which are united to one another along their sides. In the Apple the five styles are united at their base, but in the Pear they are free.** + +A flower with five stamens and a pistil. +A cross-section of a flower showing the carpels and pistil. +A close-up view of a single stamen. +A close-up view of a single carpel. +A close-up view of a single carpel, showing the style and stigma. +A close-up view of a single carpel, showing the style and stigma. +A close-up view of a single carpel, showing the style and stigma. +A close-up view of a single carpel, showing the style and stigma. +A close-up view of a single carpel, showing the style and stigma. +A close-up view of a single carpel, showing the style and stigma. + +Fig. 109.—A. Twin of Apple; B. longitudinal section of flower; C, flower, with calyx removed; D, view of flower from below; E, a single stamen; F, pistil, with calyx removed; G, one-fifth part of A; H, calyx, 1/5 part of A; i, calyx; j, style; k, ovary. + +**Fruit.—After pollination the calyx tube which surrounds the pistil swells up and produces an inferior fruit known as a **pome**.** + +**Pear.—The fruit is similar to that of the Apple.** + +**Pistil.—The pistil differs from that of the Apple in consisting of only two carpels instead of five.** + +**Pear.—The portion of the receptacle surrounding the carpels becomes enlarged into a stone endocarp. Thus, the fruit is a stone-fruit with two stones.** + +**Ladys' Mantle (Alchemilla) — The stamens are definite, and the anthers are uncielled.** + +262 +BOTANY FOR BEGINNERS +CHAP. + +Properties of Rosaceae—The seeds of many species contain prussic acid in small quantities, but the Cherry Laurel contains this acid in the leaves, and if these are eaten they produce intoxication. A very large number of the plants of this order are used in medicine. + +Rosaceae Cultivated for their Fruits. +Apple and Fruit—Pyrus. +Almond, Prunus dulcis—Merton—Anacardiaceae. +Cherry, Apricot and Plum—Prunus. +Strawberry—Fragaria. +Raspberry and Blackberry—Rubus. + +Natural Order: Umbelliferae (Parley Family).—All the plants of this order are herbs with alternate leaves, generally compound, and with umbels of flowers, usually a compound umbel, and an involucre of bracted whorled bracts. The flowers are small and white, yellow, or purple; calyx 5-lobed; corolla tubular, 5 lobed and superior. The corolla is polypetalous, there being 5 epigynous petals (1), 5 hypogynous petals (2), and 5 stamens (3). The fruit is a schizocarp (p. 238) 2-4 celled, each cell consists of a carpel, 2 styles, and 1 ovule in each cell of the ovary. + +Fig. 130.—Floral Diagram. +Fig. 130. N.C.(A.S.T.) + +Description of a typical plant of the Umbelliferae (Hercules' Spindlewood, Cow Parsley). + +**Habit.**—A coarse hairy plant with small white flowers in compound umbels. + +**Root.**—A tap-root with numerous branches. + +**Stem.**—Herbaceous, erect, hollow, ribbed, green, and green. + +**Leaves.**—Simple, alternate, sessile, entire, with long sheaths which clamp the stem ; stipulate. + +**Inflorescence.**—Indeterminate, compound umbels. + +**Buds.**—Small, greenish flowers in involucres at the base of the main umbel, and partial involucres at the base of the secondary umbels. + +**Flower.**—Complete, actinomorphic, small, white or yellow ; the outer flowers may be zygomorphic. + +**Calyx.**—Gamopetalous, 5 lobed, superior, green and hairy. + +**Corolla.**—Polypetalous, 5, epigynous. + +XIX THE CLASSIFICATION OF PLANTS 263 + +*Andracium.*—Free, 5. epigynous, alternating with the petals. +*Gymnacium.*—Symplocarpous, carpels 2, inferior, ovary two-celled, with one ovule in each cell. +*Praefl.*—The fruit is a schizocarp which splits into two meri- +carps. Seeds with endosperm. + +A plant with long, narrow leaves and a central stem with a cluster of small, white flowers. +Fig. 254.—Water-Parsley (Gium haidudum) (Half nat. size.) (S.) + +Pollination.—The flowers are small and crowded together. Honey is produced by an enlarged disc, the nectary. The honey being freely exposed, the flowers are visited by short- +noeled insects, which cross-pollinate the flowers. The principal insects which visit the flowers are flies, beetles, and wasps. + +264 +BOTANY FOR BEGINNERS +CHAP. XIX + +Properties of Umbelliferae.--Many are noted for their poisonous properties. Some are very dangerous in the wild state but harmless when domesticated; others are harmless in the wild state but deadly by being deprived of light; the poisonous matter is not produced; light seems to be necessary for its production. The principal poisonous plants belong to this order. + +Poison Hemlock (Conium maculatum).--A glabrous herb, often more than two feet high, with a stem usually covered with a white or yellowish bloom. The leaves are often spotted with purple. If the plant is bruised it emits a disagreeable smell, which is said to be similar to that of the poison of Aesculus and by it Socrates met his death. + +The Water Hemlock (C雄stus aquatilis).--This plant grows along the sides of ponds and ditches, and is the most dangerous of all poisonous plants. It has a stem about three feet long, with large green cavities. The leaves are large and tripinnate, and the narrow and lancolate leaflets are also tripinnate. + +The False Hemlock (Conium maculatum).--This plant differs from true Parsley in having white instead of yellow flowers. It often grows as a weed in gardens, and is sometimes planted as a garden plant, but it produces intoxication. + +The Water Cress (Eremogeton cernuus).--This plant grows along the edges of ditches and marshes, and flowers in July. It is very much like Caltha, but the leaves are smaller, the stems are thick at the base, thick at the thumb, and the juice is either yellow or colourless. The stem is from two to three feet high, thick, branched, and grooved. The plants should be gathered in May. + +Useful Species of Umbelliferae.--Many of the Umbelliferae are useful. Among these members may be mentioned: + +Carrot. +Fennel. +Caraway. +Coriander. + +[For Summary and Questions, see end of next chapter.] + +CHAPTER XX + +CLASSIFICATION OF PLANTS (Continued) + +Sub-classt Gamopetalae. + +Natural Order: Composite (Composite Family). + +The plants of this order which belong to the British flora are herbs. Their leaves are various and ex- +tremely variable, but they are usually in heads. The calyx is small or absent; in some cases it is replaced by a pappus of hairs or scales. The corolla is composed of 5 petals. The 5 stamens are synnemous (p. 185), and epipetalous. The pistil is syn- +carpous, and consists of a single carpel, one-celled with a single ovule. Seeds ex- +albuminosus. + +Flora Britannica.—Kig. o-C(1)C(3)G(5). + +Division of Composite.-The plants of this order are divided into two sub-divisions : (a) Tubuliferae—-with the flowers ar- +monocarpous, or the ray flowers one-lipped, e.g., Daisy, Thistle, etc.; (b) Capituliferae—-with the flowers globose, +shaped, e.g., Dandelion, Hawk's-weed. + +Description of a Typical Member of Tubuliferae + +Habit.—A perennial herbaceous plant, growing in meadows. +Stem.—An underground rootstock. +Leaves.—Linear, entire, smooth, green. +Inflorescence.—Indefinite, head or capitulum (p. 168). +Flowers.—The central flowers are termed disc flowers, and + +Floal Diagram. + +26 +BOTANY FOR BEGINNERS +CHAP. + +those on the outside, ray flowers. +The disc flowers are incomplete but perfect (p. 175), actinomorphic, tubular, and minute. The ray flowers are incomplete, imperfect, zygomorphic, ligulate, and minute. +Corydalis—The disc-flower Corydalis solida, with yellow flowers. +Corolla.—The disc-flowers are gamopetalous, 5-leaved, epigynous. +The ray-flowers are gamopetalous, 3 lobed (may consist of five petals), egypious. +Androceras.—The disc-flowers—stamens, syncy nous, 5, epipetalous. +The ray-flower, stamens absent. +Zygomorpha.—In both rays- and disc-flowers—Sarcospurum, +carpel 2, inferior, style 2, fadl. +Pollination.—The disc-flowers are protandrous. The pollen from the anthers passes into the tube formed by the united anthers and thence, when the style pushes its way up the tube, are attached to the head by the ray-flowers, which make the head very conspicuous. The insects creeping over the surface of the inflorescence pick up the pollen on their bodies and in so doing cross-pollination takes place. If not pollinated in this way, the style turns down and touches the pollen, and self-pollination occurs. +Description of a typical member of Liguliflorae. +[Taraxacum Des-mont.-Landeck] +Habit.—A perennial herb which contains a milky fluid; radical leaves. A broad radula peduncle, carrying a head of bright yellow flowers. +Stem.—A short tap-root, is capped with a short erect thicke +Leaves.—Radical, simple, runcate. +Inflorescence.—Indefinite, head of from 100 to 200 flowers. +Flowers.—Complete, zygomorphic, ligulate, small, yellow. +Calyx.—Represented by a pappus of hairs. +Corolla.—Gamopetalous, 5-lobed, epipetalous. +Androceras.—Syncy nous, 5, epipetalous. +Gymnocorm.—Syncy nous, carpell 2, inferior, style 2, stigma 2-fid. + +xx THE CLASSIFICATION OF PLANTS 267 + +**Fruit.**—The fruit is a one-sided indehiscent achene and carries a pappus of hairs, which is a modified calyx. + +**Pollination.**—The description of the pollination of the Daisy holds good for the Dandelion. + +A diagram showing the structure of a dandelion flower. +Fig. 256.—Dandelion (T. repens). 1, Two inflorescences and a leaf; 2, a flower; 3, both 1 and 2 united, with one fruit. (Q.) + +**Properties of Compositae.**—Many are used in medicine, and a few only are poisonous. The leaves contain a bitter juice, and an ill-smelling latex which is slightly poisonous. + +**Flowers.**—The daisy is the largest in the vegetable kingdom, and the best defined of all the natural orders. There are some 12,000 species all agreeing in having their flowers in heads and their stamens symmetrical. A few plants of this order are + +xx + +268 +BOTANY FOR BEGINNERS +CHAT. + +cultivared either for food or for ornamental purposes. The following are some of service to man: + +Sunflower (Helianthus annuus), cultivated for its seeds, which yield valuable oil. +Jerusalem Artichoke (I. tuberosa), cultivated for its tubers. It only grows in the warmer parts of Europe and America. +Garden Chrysanthemum (Chrysanthemum indicum), cultivated for ornament. +Cherry (Cerasus vulgaris), useful for its roots, which are dried in kales, roasted and mixed with milk as a remedy for salve. +Lettuce (Lactuca sativa), useful for salad. + +Other Compostive which are Cultivated in Gardens: +Chloraea. +Hibiscus. +Guillardia. +Callicarpa. + +Natural Order : Primulaceae (Primrose Family).—The plants of this order are herbs with radical leaves. The flowers are actinomorphic and showy. The calyx is usually 5-lobed. The corolla consists of 5 petals, which are gamopetalous and hypogynous. The five stamens are united into a tube, which is petalous. The pistil is syncarpous, has five carpels, and is superior. The ovules are numerous and free central placentaion occurs. The fruit is a capsule or a slightly capitate. The fruit is a capsule. + +Description of a Typical Plant of Primulaceae (Pri- +mula vulgaris, Primrose). + +**Habit.—A herbaceous perennial plant with radical leaves and shiny grey-green foliage.** + +**Root.—Fibrous, forming a dense mass.** + +**Stem.—A stout erect rhizome.** + +**Leaves.—Oval to oblong-lanceolate, reticulate-veined; margin crenated ; dark green above and light green below; exstipulate.** + +**Inflorescence.—Definite, solitary.** + +**Flowers.—Small, white or pale yellow; tubular ; 1 inch in dia- +meter ; dimorphic pale yellow, and sweet scented.** +Calyx—Gamopetalous, 5 lobed, inferior, apex of lobes acute, +ridged, green and hairy. + +A small illustration of a flower from the Primulaceae family. + +xx THE CLASSIFICATION OF PLANTS 269 + +Corolla—Campanulate, 5 lobed; hypogynous, lobes divided. +*Andricum.*—Free, 5, facing the lobes of corolla, epipetalous. +*Gymnium.*—Syncarpous, carpels 5, superior, style long or short, stigma capitate, ovules numerous, free central placentation. + + +A: A flower with five petals and five stamens. +B: A flower with five petals and five stamens. +C: A flower with five petals and five stamens. +D: A flower with five petals and five stamens. + + +Fig. 23.—Petunia (Petunia). A, R adical leaves and flowers; B, flower; C, stamens; D, pistil. The flowers are very showy. (Reddish.) use. + +**Fruit.—A capsule. Seeds with endosperm.** + +**Pollination.—Cross-pollinated by insects (p. 209-10); Self- +pollination is possible in the short-styled form.** + +**Properties of Primulaceae.—The properties of the plants of this order are unimportant. The tubers of *Cydamenum* are poisonous, but after cooking they are perfectly harmless.** + +270 +BOTANY FOR BEGINNERS +CHAP. + +**Natural Order:** Boraginaceae (Borage Family).—The plants can be easily recognized by their succulent stems covered with hairs, their entire leaves and scor- +poid cymes. The flowers are generally white, blue, or purple, in cymes or corymbs, the corolla gamopetalous, 5 lobed, inferior. +A +Fig. 239.—Floral diagram. +The corolla is gamopetalous, 5 lobed, and imbricate, the petals imbricate and alternate with the lobes of corolla. The pistil is syncarpous, 3-carpellate, the carpels 3, the fruit consists of four free carpels (p. 186). +The style is syngamous (p. 186). +**Floral formula.**—K(5),C(3),A(5),G(3). +**Description of a Typical Member of Boraginaceae.** **Myosotis palustris, Forget-Me-Not.** +**Habit.**—A perennial herb with entire leaves, and bright blue flowers. +**Root.**—Rootstock creeping. +**Stem.**—Stem erect or ascending with small leaves. The aerial stem grows to 1 to 2 feet high; herbaceous, erect, ribbed, hollow, hairy, green. +**Leaves.**—Cadulete, alternate, sessile, simple, entire, hairy, green. +**Inflorescence.**—Definite, scapoid cyme. +**Flower.**—Complete; actinomorphic; rotate, minute, blue, throat of corolla filiform. +**Calyx.**—Gamopetalous, 5 lobed, inferior, green, hairy. +**Corolla.**—Gamopetalous, 5 lobed, hyponymous. +**Androecium.**—Pistillate; 3 stamens; alternating with lobes of corolla, filament short. +**Gynaeceum.**—Syncarpous; 2 carpels, superior ovary; 5 lobed, stigmas 3. +**Fruit.**—Four indehiscent nutlets. +**Pollination.**—By insects. + +**Properties of Boraginæceæ.**—The properties of the plants of this order are unimportant. The dried root of *Albastrum*, cultivated through- +out the south of Europe, is used in medicine. + +A floral diagram showing the structure of a typical member of the Boraginaceae family. + +xx +THE CLASSIFICATION OF PLANTS +271 + +Other Boraginaceae which should be noticed. + +Viper's Bugloss - Echium vulgare. +Borage - Borago officinalis. +Gentian - Gentiana cruciata. +Crownwort - Lithospermum officinale. +Longwort - Lycopus europaeus. +Madwort - Artemisia punctata. + + +A: A branch, with inflorescence ; B, flower ; +C: corolla and stamens from above ; D, section of stem ; E, longitudinal section of flower. + + +Fig. 60. - *Lithospermum* (Myosotis). + +Natural Order : Scrophulariaceae (Foxglove Family)... + +The plants of this order are herbs, with simple toothed leaves, which as a rule are alternate. The inflorescence may be soli- +tary, axillary, or a raceme. The flower is zygomorphic, and very often bilabiate. The calyx is gamosepalous, 5 lobes, infundibular. +The corolla is gamobasallicous, 3 lobes, hypogynous. The stamens are usually 4 (in Veronica), ditysamous (p. 185), epigynous. +The pistil is syncarpous, carpels 2, superior ; style terminal, + +272 + +275 +BOTANY FOR BEGINNERS +CHAF. + +ovary two-celled, ovules axile placentation. The fruit is a capsule. +Floral formula.—K(5):[C(3), A(3)♀(2)], or K(4):[C(4), A(3)♀(2)]. +Description of a Typical Plant of the Scrophulariaceae. +**Scrophularia nodosa Linn.** +**Habit.**—A tall perennial herb, which flowers from July to September. +**Fam.**—Herbaceous, erect, round, green. + + + Image 1 + Image 2 + Image 3 + Image 4 + + +**Fig.**—Sta.—Fagulae (Dulichium purpureum). a, Flower; b, corolla cut open and spread out; c, calyx cut profile; d, fruit; e, section of fruit. (S.) + +**Lorazus.**—Lower ones radical and stalked; upper ones cauline and sessile. +**Inflorescence.**—Indefinite ; raceme. +**Flower.**—Complete, zygomorphic, tubular, large, purple, with spots inside. +**Calyx.**—Gamosepalous, 5 lobed, inferior. + +xx THE CLASSIFICATION OF PLANTS 273 + +Cerella—Gomopetals ; 5 lobed, hypogynous ; the lower lip of cerrella is longer than the upper lip. +Andracumum—Free, 4 stamens, diadelphous, epipetalous, filaments numerous, anteriors 2-budded. + +Corydalis—Sympetals ; 3 carpels, superior, style terminal ; stigma 2-lobed ; ovules 1-celled ; ovules numerous ; axis placenta-tal. + +Fritillaria—A two-valved bulb. + +Pollination.—The flower is protandrous, and is pollinated by humble-bees, which creep into the flower and are dusted with pollen on their backs. + +EXCEPTIONS TO THE ABOVE TYPE. + +Speedwell (Veronica)—Opposite Inflorescence—Either an axillary or a terminal raceme : Cerella—Pods 4-lobed unequal ; +Mullein—Verbascum (Verbascum) +Lupin—Lupinus (Lupinus) + +The *Spiraeae* of *Sperberia*—No flowering plants of this order are poisonous, but some are used in medicine. +Most poisonous is the Foxglove, all parts of which are poisonous. + +A diagram showing the structure of a flower. +Fig. e6.—Speedwell (Veronica). A, branching raceme; B, flowers; C, calyx; D, corolla; E, stamens; F, receptacle; G, ovary of Speedwell. + +Many of the plants are root-parasites, and are provided with suckers which penetrate into the roots of the host plant, e.g., Yellow Rattle, Cow-Whisker, Eyebright, and Lousewort. + +T + +274 +BOTANY FOR BEGINNERS +CHAP. + +Natural Order : Labiatæ (Labiate Family).—The plants of this order can be recognised by their square stem and opposite leaves. The inflorescence is a verticillaster (p. 173). The flower is zygomorphic. The calyx is gamopetalous, 5 lobed, and imbricate, the outer two free, the inner three united and two-lipped. The stamens (2 or 4) are epipetalous ; if four, didynamous. The pistil is syncarpous, carpels 2, superior, style symphorous, stigma terminal. The ovary is inferior. + +NOTE.—The Labiate can be distinguished from the Scrophu- +lariaceae by their square stem and opposite leaves, and by the +bilateral symmetry of the flowers, from the Inflorescence by +the stamens being fewer in number than the lobes of corolla, +and by the zygomorphic flowers. + +Floral Formula: A(1), B(1), C(2), D(2), G(2). + +Description of a Typical Plant of the Labiatae (Lamiaceum album, White Deadnettle). + +Habit.—A perennial. +Leaf.—Narrow with square stem and coarse foliage. +Stem.—Herba- +ceous, erect, square, +hollow, hairy, +green. + +A small circular diagram with a central cross and surrounding text: "Flax, etc., -Floral diagram." + +A small circular diagram with a central cross and surrounding text: "Flax, etc., -Floral diagram." + +Leaves.—Cauline, opposite, simple, cordate, serrate, hairy. +Inflorescence.—Definite ; verticillaster. +Flower.—Complete, zygomorphic, $\frac{1}{4}$ of an inch in diameter labiate, white, faintly scented. + +xx THE CLASSIFICATION OF PLANTS 275 + +Calyx--Gamosepalous, 5 lobed, inferior, lobes acute, hairy green. + +Corolla--Gamopetalous, 5 lobed, hypogynous, very hairy. +Androecium--Free, 4, ditynamous, epipetalous, filaments equal. +Stamens--Free, 4, ditynamous, epipetalous. +Gynoeceum.--Sympetalous, carpels 2, superior, style gynobasic; stigma 2-dentate, ovary 4-lobed; 1 ovule in each cell of ovary. + +Flower.--The flower is pollinated by humble-bees, which creep into the flower to suck the honey from the nectary. As the bee creeps through the flower he touches the stamens and the after- +wards darts with his proboscis into the nectary. Thus the pollination is effected. + +**Pollination of Lupinus.**—None of the plants of this order are polli- +nated; many species possess essential oils which are formed by glands in the tissues of the leaves. The oil can be separated by distillation. +Many of these plants are used as medicinal herbs and tonics, such as +Mint, Pennyroyal, Majapahit, Thyme, Sage, and Balm. + +Sub-Class: Incomplete. + +**Natural Order:** Cupuliferae (Oak Family).—The plants of this order include most of the shrubs and trees found in the temperate regions of the globe. The leaves are simple, mucous- +cous or leathery; they are often alternate or opposite; the flowers are small and inconspicuous. The perianth is either absent or small and green. The stamens vary in number from one to many; the pistil is usually a single ovary with one or two ovaries either 2 or 3 celled, with 1 or 3 ovules in each. The fruit is often a seedless, indehiscent—a nut. Many plants of this order produce seeds without a fruit. + +**Description of a typical Member of the Cupuliferae.**—(Corylus Avellana, Hazel.) + +The tree is about 10 feet high; it has alternate leaves with monocious flowers; the main stem breaks up into branches just above the ground. + +Root.--The primary root of the seedling grows only for a short distance; then it becomes dormant and lies along run just beneath the surface soil in a horizontal manner. + +Stem.--The base of the stem beneath the ground gives off suckers (p. 21) which grow upwards, and from their lower side adventitious roots are produced. If from any root on the + +A small illustration showing a typical member of the Cupuliferae family. + +276 +BOTANY FOR BEGINNERS +CHAP. + +connecting portion between the old plant and the new shoots is destroyed, new plants are formed. +*Leaves.*—Cauline, alternate, simple, cordate, serrate ; the small stipules fall off as the leaf expands. +*Inflorescence.* The *male* flowers are arranged in a spike as a catkin (p. 170). + + +A diagram showing the structure of a plant with a male flower at the top left, a female flower at the bottom right, and a cluster of small leaves in the center. + + +Fig. 266.—Hand (Caryophyllus), *Flowering branch* : a male flower [3] & a stamen ; +a. a female flower [2] and 6. fruit ; 7. a stipule leaf. (cf.) + +The *female* flower appears as a small bud, recognised by the coloured stigmas protruding from its apex. +*Flower.*—The male flower is incomplete, imperfect (p. 178), and very minute. +The *female* flower is imperfect, incomplete, and minute. + +xx THE CLASSIFICATION OF PLANTS 277 + +**Persicaria.**—The **male flower** possesses no perianth ; the **stamens** are fixed on a *bract*. + +The **female flower** possesses a minute gamopyleous perianth inserted on the ovary and therefore epigynous. +Of the stamens, each is free from the other to branch, each anther is deeply lobed, so that there appear to be eight stamens. + +**Carpinus.**—Female flowers—syncarpous, carpels 2, inferior style long, stigma red ; the ovoids develop after pollination. + +**Fruit.**—A **berry**. + +**Anemone.**—The *Haze* and its relations are pollinated by the wind. That this may take place without difficulty the flowers are produced before the foliage leaves. The Hazel flourishes in spring, and early April. + +**Properties of Cupressus.**—The wood of some few species of Oak, and Acorn, are used in medicine. The plants of the order are harmless, and those of the family are poisonous. + +**Economic importance of Cupulifera.**—This order is of great economic value. The wood of the Oak is used very largely because of its hardiness, and because it is suitable for making furniture. The bark is used for tanning. Cork is also obtained from the Oak. The Beech produces nuts which are used for food. The Chestnut is edible, and forms a most important article of food in the South of Europe. + +**Class : MONOCOTYLEDONS.** + +Sub-class : Petaloideae. + +**Natural Order : Lilicoene (Lily Family).**—The plants of this order are succulent herbs with perennial bulbs or rhizomes. +The leaves are large and showy, often variegated. The inflorescence may be solitary or a raceme. The flowers are large, usually white or pale-coloured. The perianth consists of five leaves arranged in two series. The petals are usually arranged in two series. The pistil is syncarpous, carpels 3 ; ovary superior, style unbranched, stigma 3-lobed, ovoids in axile placentation. + +Floral Formula.—[P+3 A+3 G+3] + +**Description of a Typical Flower of the Order Lilicoene.**—(Hymenocallis Nonscripta, Wild Hymenocallis or Bluebell.) + +A typical flower of the Lilicoene order. + +278 +BOTANY FOR BEGINNERS +CHAP. + +Habit.—A perennial herb with an underground bulb, narrow radical leaves, and a raceme of sweet-smelling blue flowers. +Roots.—Adventitious roots are given off from the bulb. +Stem.—An underground bulb (p. 23). +Leaves.—Radical, simple, narrow, entire, green. +Flowering.-—Indefinite, raceme. +Bracts.—Bracteate, blue, one at the base of each petal. +Petals.—Complete, actinomorphic, bell-shaped, blue. +Perianth.—Gamophyous (base only), 6 lobed, blue. +Androecium.—Free, 6, in two series, epipetalous, filament blue, anther 2-lobed, versatile. + +Fic. 165.—Floral diagram. + +Fic. 166.—Flower of White Lily. + +Fic. 167.—Longitudinal section of Flower of White Lily. + +Gymnism.—Syringocarpus, carpels 5 superior, style long, stigma 3-lobed, ovary 3-celled, ovules axile placentation. + +XX THE CLASSIFICATION OF PLANTS 279 + +Fruit.--A capsule, seeds albuminous. +Pollination.--The flowers may be pollinated by insects, or + + +A flower with three petals and a central column. +B A section of the flower showing the stamens and pistil. +C A section of the fruit showing the ovary and style. +D A section of the fruit showing the ovules. +E A section of the fruit showing the ovary and style. +F A section of the fruit showing the ovules. +G A section of the fruit showing the ovary and style. +H A section of the fruit showing the ovules. +I A section of the fruit showing the ovary and style. +J A section of the fruit showing the ovules. +K A section of the fruit showing the ovary and style. +L A section of the fruit showing the ovules. +M A section of the fruit showing the ovary and style. +N A section of the fruit showing the ovules. +O A section of the fruit showing the ovary and style. +P A section of the fruit showing the ovules. +Q A section of the fruit showing the ovary and style. +R A section of the fruit showing the ovules. +S A section of the fruit showing the ovary and style. +T A section of the fruit showing the ovules. +U A section of the fruit showing the ovary and style. +V A section of the fruit showing the ovules. +W A section of the fruit showing the ovary and style. +X A section of the fruit showing the ovules. +Y A section of the fruit showing the ovary and style. +Z A section of the fruit showing the ovules. +AA A section of the fruit showing the ovary and style. +AB A section of the fruit showing the ovules. +AC A section of the fruit showing the ovary and style. +AD A section of the fruit showing the ovules. +AE A section of the fruit showing the ovary and style. +AF A section of the fruit showing the ovules. +AG A section of the fruit showing the ovary and style. +AH A section of the fruit showing the ovules. +AI A section of the fruit showing the ovary and style. +AJ A section of the fruit showing the ovules. +AK A section of the fruit showing the ovary and style. +AL A section of the fruit showing the ovules. +AM A section of the fruit showing the ovary and style. +AN A section of the fruit showing the ovules. +AO A section of the fruit showing the ovary and style. +AP A section of the fruit showing the ovules. +AQ A section of the fruit showing the ovary and style. +AR A section of the fruit showing the ovules. +AS A section of the fruit showing the ovary and style. +AT A section of the fruit showing the ovules. +AU A section of the fruit showing the ovary and style. +AV A section of the fruit showing + +280 +BOTANY FOR BEGINNERS +CHAP. +EXCEPTIONS TO THE ABOVE TYPE. + +This order is a very large one, and there are many species which depart more or less from the type. The following are some of the most remarkable: + +**Butcher's Broom (Aruncus odoratus).** This is the only British member of this order, and is a shrub with a very peculiar pro- +portion of a new meristem layer in the cortex : *Leaves.* The leaves are very minute, bearing in their axils head-like clusters (cubules). + +A flower with three petals and a long tube. +B longitudinal section of flower. +C flower viewed from above. +D transverse section of stem. + +Flowers.—The flowers are minute, and are produced on the face of the cladode : *Stamens.* There are only 3 stamens, and the filaments are united into a sheath. + +**Herb Paris** (Paris quadrifolia).—This plant differs from monotro- +phous plants in having the parts of the flower in fours, and its leaves whorled. The leaves are simple, and have 3 leaflets each ; but vary from 3 to 5 in each wood : *Stamens.* There are usually 3 stamens, but these vary from 6 to 10 : *Filaments.* There are 4 carpels. + +A daffodil with 6 petals. +B longitudinal section of flower. +C flower viewed from above. +D transverse section of stem. + +xxi THE CLASSIFICATION OF PLANTS zxi + +Properties of Lilaceae.—Many of the plants in this order are poisonous, +and few are used in medicine. The principal poisonous plants are: + +**Medow Saffron (Colchicum autumnale).**—This plant possesses a sub- +stance which is poisonous to man, but which is harmless to animals. It appears +in August and September; the fruit and leaves fall over in spring. The +plant is very common in Europe and Asia, and contains the largest quantity of the poisonous material. + +**Lilac (Syringa vulgaris) and Lily of the Valley (Convallaria majalis)**, are also poisonous. +The **Bull's-bit (Dentaria bulbifera)** is a poisonous plant, and also the +bark of the **Crown Imperial (Piptanthus imperialis)**. + +**Natural Order : Amaryllidaceae** (Daffodil Family).—These +plants have the same characters as the Lilaceae, with the excep- +tion of the pistil, which is Inferior. Many of the members of this order are used for medicinal purposes, which is an outgrowth of the perianth. + +*Floral formula:* 3-5 A + 3C + 3G + +Plants belonging to Amaryllidaceae.—The plants of this order do not need any special description, they are so much like the Lilaceae in every respect except the pistil. Well known plants belonging to this order are the **Orchid Lily**, **East Lily** +(Lycoris radiata), **Snow-flake** (Galanthus nivalis), and the **Snow-drope** (Leucojum aestivum). + +SUMMARY. + +The Natural System of classification is based on the resemblances and differences of plants. + +Classification. + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
The Plant Kingdom.PhanerogamsCryptogams
AngiospermsDicotyledonsGymnosperms
Each divided into a number of OrdersThalamiiferae (including Monocotyledons)Pedaliaceae (including Liliaceae)
IncompletumSphaeridae (including Liliaceae)
IncompletumOrder
+ +282 +BOTANY FOR BEGINNERS +CHAP. XX + +A natural order consists of a number of genera which possess some common character. + +A genus consists of one or more species which resemble one another in some particular way. + +A species includes plants which must have descended from a common ancestor. + +QUESTION ON CHAPTER XIX AND XX. + +(1) What is the chief distinction between Monocotyledons and Dicotyledons? (1858.) + +(2) Describe and compare the corollas of any three of the following plants: - the Cabbage, the Rose, the Poppy, the Honeysuckle, the Larkspur (Larkspurum), Monkshood (Aconitum), Sweet Pea (Lathyrus), the Balsam (Impatiens), the Hellebore (Helleborus). + +(3) Describe and compare the fruits of the Wallflower (Cherubimia), the Poppin'gloss (Papaver), and the Dandelion (Taraxacum). To what natural orders do these plants re- +spectively belong? + +(4) Describe the general structure, position, and pectination of the ovary in the Umbelliferae, the Leguminosa, and the Labiate. (1851.) + +(5) Describe the general arrangement of the stamens in the flowers of the Cruciferae, the Compositae, and the Primulaceae. (1861) + +(6) Give a general account of the structure of the flower of a Legu- +minosae. (1857.) + +(7) Describe carefully the structure of a leaf bud in any member of the Cruciferae. (1857.) + +(8) Describe the arrangements of the stamens in the flowers of the Rutaceae, the Asteraceae, and the Sweet Pea. Refert these plants to their natural orders. (1857.) + +(9) Mention instances from the following natural orders of flowers, in which there is a difference in number of petals: - 1st, The Cruciferae; 2nd, that of the plants, explaining in each case how the difference in number is accounted for by analogy with Scrophularia and Labiate. (1860.) + +(10) Describe with examples (a) a hypogynous, (b) a perigynous, and (c) an epigynous flower. (1856.) + +(11) Explain why there is no such distinction in the Cruciferae, the Leguminosae, and the Lilaceae. (1857.) + +(12) How do the plants of the natural order Amaryllidaceae differ from those of the Lilaceae? + +CHAPTER XXI + +PLANT DESCRIPTION + +The Importance of Plant Description.—The import- +ance of practical work in all branches of science is now uni- +versally admitted, and in Natural Science it is the only way to obtain a correct knowledge of the subject. It is therefore specially +written for those persons who are willing to verify the principal +facts of botany by an appeal to Nature herself. Plant description +forms one of the most agreeable and useful modes of approaching Nature. +The student may learn much with the aid of a Herbarium, many +plants in a Herbarium, but to learn direct from Nature her +secrets, is always interesting. It is only by constant intercourse +with Nature that we can hope to acquire a true knowledge of her. + +The able naturalist Goethe made the following remark: " Man +Sieht nur was man weiss," the trained naturalist goes about +and does not know what he sees. + +Apparatus Necessary for Plant Description.—The apparatus necessary to examine the external parts of plants are of two kinds, viz., (1) Apparatus for examining the leaves, +(2) Apparatus for examining the flowers. + +(1) A sharp knife is necessary for making sections of stems, +flowers, buds, and ovaries. + +(2) Needles; the three-sided glover's needle, which is used for cutting +the blunt end into fine twigs; when the twigs dry the needles are held tight. These are used for separating the constituent parts of flowers; for dissecting flowers, and for making the parts of flowers on paper, cork, or wood in the form of a diagram. + +(4) A hand-lens (p. 63). (5) A pair of forceps is very useful for lifting small objects. (6) A book of forms? has + +1 Evans's forms for plant description are very useful. + +284 +BOTANY FOR BEGINNERS +CHAP. + +plant description is very useful, because it keeps the attention of the student fixed on the most essential points. (2) A blank drawing book and pencils will enable the student to make sketches of the different parts of the plant. +(3) Drawings should be made with little practice; a good description of any ordinary plant should be made in about three-quarters of an hour. Slowness should always be avoided, and the student should make his work neat, which is important, which are present. To make certain that a good method of work is ensured the following plan should be followed. + +A PLAN FOR DESCRIBING PLANTS + +(1) Habit—Whether annual, biennial, or perennial ; herbs, shrubs, or trees (p. 101). +(2) Root—Kind (p. 53). Whether a tap-root; size, shape, and branching (p. 54). +(3) Stem—Kind (p. 67). Whether erect, prostrate, ascending, or creeping (p. 68). +(4) Shape—round, ribbed, square, etc. +(5) Leaves—Kind (p. 70). Whether simple or compound; whether entire or toothed; whether smooth or hairy; whether alternate or opposite; whorled or spiral arrangement. +(6) Stems or compound (p. 83). +(7) Compound of leaf—perfect, petiolate, sessile. +(8) Shape of leaf (p. 84). +(9) Variation of leaf (p. 84). +(10) Color of leaf—hairy or smooth, green, or light green. +(11) Stipules or stipelike (p. 45). +(12) Inflorescence—whether definite or indefinite (p. 166-172). +(13) Bracts—whether present or absent. +(14) Flower—whether complete or incomplete (p. 175). +(15) Pedicel—whether long or short; whether sympetalous (p. 179). +(16) Shape. +(17) Diameter, colour, perfume. +(18) Calyx—whether polysepalous or gamopetalous (p. 183). +(19) Number of sepals. +(20) Whether inferior or superior (p. 183). +(21) Corolla—whether polysepalous or gamopetalous. +(22) Number of petals. +(23) Whether superior, hypogynous, perigynous, or epigynous. +(24) Shape of petals or leaves of corolla. + +XXI +PLANT DESCRIPTION +285 + +**Auracium**—(a) Whether free, monopodial, diadelpous, or polydaphous (p. 181). +(b) Whether simple or indefinite. +(c) Whether hypogynous, perigynous, epigynous, epipetalous, or Sympodium. +(d) Shape and length of filaments. +(e) Whether anther two-celled, and how fixed to filaments, introrse or extrorse. +(f) Whether monocarpous, apocarpous, or syncarpous. +**Gymnium**—(a) Whether monopodial, apocarpous, or syncarpous. +(b) Number of carpels. +(c) Whether stamens superior (p. 186). +(d) Whether axis long or short. +(e) Whether one- or two-celled (p. 264), 3-fid., 4-fid., &c. +(f) Whether ovary one, two, three, or more celled. + +**Ovule**—(a) Placentation—axile, parietal, free-central, or basal (p. 187). +Flora Formis (p. 188). +**Fragaria**—(p. 190) +Classification—Place the plant in its true position in the natural series. + +Sub-Kingdom +Division +Class +Sub-Class +Name +Genus. +Species. [If possible name the plant.] Common Name. + +**EXAMPLE OF PLANT DESCRIPTION** + +**Habit**—An erect perennial herb, with radical leaves, growing in damp ditches or marshy places. + +**Root**—Absent. + +**Stem**—Herbaceous, erect, ribbed, twisted, solid, hairy, becoming woody at base. + +**Leaves**—Radical leaves creased, pinnate, pinnatifid, reticulate-veined, cauline leaves alternate, compound, ternate ; the terminal leaflets usually larger than the lateral ones; upper side dark green and under side light green, stipules, stipules adnate, small and lobed. + +**Inflorescence**—Compound umbel-like; two-flowered cyme, drooping. + +**Flower**—Complete; actinomorphic; roughly campanulate, $\frac{4}{\text{an inch}}$ of an inch diameter, honeyed, dull orange, protandrous. + +s6 +BOTANY FOR BEGINNERS +CHAP. XXI + +**Calyx:**—Gamousopetalous, to lobes, 5 alternating, lobes small, infertile, lobes toothed, hairy, reddish brown. +**Corolla:**—Polypetalous, 5 lobed, perigynous, petals triangular in shape, vine-like, alternating with lobes of calyx. +**Androecium:**—Perigynous, stamens numerous, filaments long, stigmas short, anthers lobed and versatile, introrse, the outer whorl opening first. +**Gynaeceum:**—Perigynous, carpels numerous, superior, styles long, filiform, stigma terminal and coloured. +**Ovule:**.—One ovule in each carpel, placentation basal. +**Fruct.:—Not developed.** +**Ephemeral Plant.** [X (j) s C A = J G 8] +Floral Diagram. (p. 25.) + +**CLASSIFICATION** + +Sub-Kindred: *Phanerogamae.* I place this plant in the above sub-kindred because it is a flowering plant. +Division: *Angiospermae.* I place this plant in this division because it is a flowering plant. +Class: *Dicotyledonea.* I place this plant in the above Class because the leaves are reticulate-vined, and the parts of the flowers are opposite. +Sub-Class: *Calyciflorae.* This plant belongs to this sub-class because the petals and stamens are inserted on the calyx and are opposite. + +Natural Order: *Rosaceae.* This plant belongs to this natural order, because of the indefinite stamens (which are perigynous), and its apocarpyous pistil; the perigynous stamens distinguish it from a *Caryophyllaceae*. + +Genus: *Geum.* +Species: *G. vulgare.* +Common Name: *Water Aven.* + +For other examples see Chapters on Classification. + +INDEX + +**AMORPHOUS, by 600s, 137** + +- **Apothecium**: 128 +- **Aphelostomus**: 128 +- **Aphrodite**: 128 +- **Aphroditea**: 128 +- **Aphroditeae**: 128 +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 129** +- **Aphroditeae, 130** + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, 600s + +**BLACKBERRY**, by 600s, _ + +INDEX + +1 + +Aductatinae, 387 +Delphiniinae, 387 +Lepidostominae, 387 +Desmidophyceae, 387 +Desmidophyceae, 387 +Drepanodictyophyceae, 387 +Drepanodictyophyceae, 387 +Euplotes, 387 +Fragilariaceae, 387 +Gymnodictyophyceae, 387 +Heterokontophyceae, 387 +Hydrodictyophyceae, 387 +Isotrichophyceae, 387 +Joubertia, 387 +Lepidostomaceae, 387 +Lepidostomaceae, 387 +Mycosphaerellaceae, 387 +Nemastomellaceae, 387 +Oedogoniales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 +Pleurosigmales, 387 + +Frulli (141) classification of algae: kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; kelp; +Interfasciculata cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem cambium: eucalyptus stem Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum Cambum CambumCambumCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambuCambUCamblCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamlCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCamblCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampalCampal Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa Campa + +Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) Gymnarchaceae (142) + +Gymnosporangiales gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order gymnosporangial order + +Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus Gymnothorax genus + +Habronema HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMA HABRONEMAHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemaHabronemahabronemahabronemahabronemahabronemahabronemahabronemahabronemahabronemahabronemahabronemahabronemahabronemahabronemahabronemahabronemahabronemahabronemahabronemahabronemahabronemahabronemahabromenahabromenahabromenahabromenahabromenahabromenahabromenahabromenahabromenahabromenahabromenahabromenahabromenahabromenahabromenahabromenahabromenahabromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenahobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaihobromenaih obro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men ai h ob ro men + +Gymnodictyophyceae family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family family + +Gymnodictyophyceae subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily subfamily + +Gymnodictyophyceae tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe tribe + +Gymnodictyophyceae genus genus genus genus genus genus genus genus genus genus genus genus genus genus genus genus genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre genre + +Gymnodictyophyceales GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALES GYMNO DICTYOPHYCEALESGYM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALESG YM NO DI CT Y OP HY CE ALE SG + +Gymnodictyophyceales clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade clade + +Gymnodictyophyceales class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class class + +Gymnodictyophyceales phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum phylum + +Gymnodictyophyceales kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom kingdom + +Gymnodictyophyceales domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain domain + +Gymnodictyophyceales life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle life cycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecycle livecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecylcylelivecy lecly cly c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y l c y + +Gymnodictyophyceales species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species species + +Gymnodictyophyceales taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon taxon + +Gymnodictyophyceales cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladogram cladagram + +Gymnodictyophyceales phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny phylogeny Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic tree Phylogenetic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo genet ic trephylo gen etic t rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct rephy lo ge net i ct reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo ge ne tic t reph yo gne tic t reph yo gne tic t reph yo gne tic t reph yo gne tic t reph yo gne tic t reph yo gne tic t reph yo gne tic t reph yo gne tic t reph yo gne tic t reph yo gne tic t reph yo gne tic t reph yo gne tic t reph yo gne tic t reph yo gne tic t + +Gymnodictyophyceales lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineage lineagelineage lineagelineage lineagelineage lineagelineage lineagelineage lineagelineage lineagelineage lineagelineage lineagelineage lineagelineage lineagelineage + +INDEX +289 + +**Mecocystis cylin, 3a, 540** +- **Mecocystis, 3a, 540** +- **Mecocystis, 3a, 540** +- **Mecocystis, 3a, 540** + +**Methanobacterium** +- **Methanobacterium, 2a, 64** +- **Methanobacterium, 2a, 64** +- **Methanobacterium, 2a, 64** + +**Methanol** +- **Methanol, 2a, 64** +- **Methanol, 2a, 64** +- **Methanol, 2a, 64** + +**Mercury** +- **Mercury, 1b, 179** +- **Mercury, 1b, 179** +- **Mercury, 1b, 179** + +**N** +- **N**, 1b, 179 + +**Nanomix** +- **Nanomix, 1b, 179** + +**Natural history** +- **Natural history, 3b, 540** + +**Nature** +- **Nature, 2a, 64** + +**Neurospora crassa** +- **Neurospora crassa, 2a, 64** + +**Nephrotoma scalaris** +- **Nephrotoma scalaris, 2a, 64** + +**Nitrogenase** +- **Nitrogenase, 2a, 64** + +**Nitrogen fixation** +- **Nitrogen fixation, 2a, 64** + +**Nitrogenase enzyme** +- **Nitrogenase enzyme, 2a, 64** + +**Nitrogenase enzyme activity** +- **Nitrogenase enzyme activity, 2a, 64** + +**Nitrogenase enzyme activity measurement** +- **Nitrogenase enzyme activity measurement, 2a, 64** + +**Nitrogenase enzyme activity measurement method** +- **Nitrogenase enzyme activity measurement method, 2a, 64** + +**Nitrogenase enzyme activity measurement method of** +- **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + - **Nitrogenase enzyme activity measurement method of**, 289 + +**Nitrification** +- **Nitrification, 1b, 179** + +**Nitrification process** +- **Nitrification process, 1b, 179** + +**Nitrification process step by step** +- **Nitrification process step by step, 1b, 179** + +**Nitrification process step by step diagram** +- **Nitrification process step by step diagram,** A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification., A diagram showing the steps involved in nitrification. + +**Nitrite nitrogen cycle** +- **Nitrite nitrogen cycle,** *The Nitrite Nitrogen Cycle* + +**Nitrite nitrogen cycle step by step** +- **Nitrite nitrogen cycle step by step,** *The Nitrite Nitrogen Cycle* + +**Nitrite nitrogen cycle step by step diagram** +- **Nitrite nitrogen cycle step by step diagram,** *The Nitrite Nitrogen Cycle* + +**Nitrite nitrogen cycle step by step flowchart** +- **Nitrite nitrogen cycle step by step flowchart,** *The Nitrite Nitrogen Cycle* + +**Nitrite nitrogen cycle step by step flowchart with labels** +- **Nitrite nitrogen cycle step by step flowchart with labels,** *The Nitrite Nitrogen Cycle* + +**Nitrite nitrogen cycle step by step flowchart with labels and arrows** +- **Nitrite nitrogen cycle step by step flowchart with labels and arrows,** *The Nitrite Nitrogen Cycle* + +**Nitrite nitrogen cycle step by step flowchart with labels and arrows and text boxes** +- **Nitrite nitrogen cycle step by step flowchart with labels and arrows and text boxes,** *The Nitrite Nitrogen Cycle* + +**Nitrite nitrogen cycle step by step flowchart with labels and arrows and text boxes and icons** +- **Nitrite nitrogen cycle step by step flowchart with labels and arrows and text boxes and icons,** *The Nitrite Nitrogen Cycle* + +**Nitrite nitrogen cycle step by step flowchart with labels and arrows and text boxes and icons and symbols** +- **Nitrite nitrogen cycle step by step flowchart with labels and arrows and text boxes and icons and symbols,** *The Nitrite Nitrogen Cycle* + +**Nitrite nitrogen cycle step by step flowchart with labels and arrows and text boxes and icons and symbols and numbers** +- **Nitrite nitrogen cycle step by step flowchart with labels and arrows and text boxes and icons and symbols and numbers,** *The Nitrite Nitrogen Cycle* + +**Nitrite nitrogen cycle step by step flowchart with labels and arrows and text boxes and icons and symbols and numbers and lines** +- **Nitrite nitrogen cycle step by step flowchart with labels and arrows and text boxes and icons and symbols and numbers and lines,** *The Nitrite Nitrogen Cycle* + +**Nitrite nitrogen cycle step by step flowchart with labels and arrows and text boxes and icons and symbols and numbers and lines and shapes** +- **Nitrite nitrogen cycle step by step flowchart with labels and arrows and text boxes and icons and symbols and numbers and lines and shapes,** *The Nitrite Nitrogen Cycle* + +**Nitrite nitrogen cycle step by step flowchart with labels and arrows and text boxes and icons and symbols and numbers and lines and shapes and patterns** +- **Nitrite nitrogen cycle step by step flowchart with labels and arrows and text boxes and icons and symbols and numbers and lines and shapes and patterns,** *The Nitrite Nitrogen Cycle* + +**Nitrite nitrogen cycle step by step flowchart with labels and arrows and text boxes and icons and symbols and numbers and lines and shapes and patterns and colors** +- **Nitrite nitrogen cycle step by step flowchart with labels and arrows and text boxes and icons + +INDEX + +Spadiceum, 243 +Spalda, 220 +Spergula, 258 +Spesitanis, 39 +Spesitanus, 39 +Spessartia, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spessartina, 276 +Spesitanus, 39 + +Supercilium + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Superiori + +Supercilium + +MACMILLAN & CO.'S +SCIENCE CLASS BOOKS +Adapted to the South Kensington Syllabus. + +I. 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