sentence: Tree rings grow under the bark, and the bark is pushed out while the tree is growing.
sentences_after: The inner part of a growth ring is formed early in the growing season, when growth is fast and is known as early wood. The outer portion is the late wood, and is denser than early wood. Many trees in places with hot summers and cold winters make one growth ring a year.
concept_name: tree ring
headings: Growth ring
categories: Trees