A transverse section of the trunk of a tree shows concentric rings which are known as growth rings. How are these rings formed? What is the significance of these rings?
Growth rings are formed from meristematic tissue of the cambium in dicot trees. Cambium is very active in the spring season, leading to the formation of a large number of xylary elements having wider vessel cavities. This wood is called springwood. In winter, the cambium activity is slowed down, leading to lesser xylary elements with narrow vessel cavities. The wood is called latewood or autumn wood.
The two kinds of wood appear together with concentric rings known as annual rings or growth rings. These rings give an estimated age of a tree.