sentence: Thorns are the ends of branches that are hard and sharp.
sentences_before: Botanists use three different words, 'thorns', spines, and 'prickles'.
sentences_after: Prickles are on the outside of stems. There are many different kinds of spines, some on leaves, some grow instead of leaves.
concept_name: thorn
headings: Spine (botany)
categories: Plant anatomy