What are meristematic tissues? Explain with the help of suitable diagram. Give their classification on the basis of their position in the plant body.
Meristematic tissue consists of cells that are capable of division and possesses totipotency-that is, capability to give rise to all cell types of the body. Its cells divide and help in increasing the length and girth of the plant.
The meristematic cells are compactly arranged and have thin cellulosic cell walls. They occur in growing regions of the plant. They are responsible for the formation of new cells of the plants and also heal the injured parts of the plants.
Meristematic tissues are classified into following three types depending upon their position in the plant body:
(i) Apical meristems: They are present at the tip of stems (shoot apex) and roots (root apex) and also in apices of leaves. They bring about elongation of root and stems; hence, they cause an increase in the length of the plant.
(ii) Lateral meristems: They are found beneath the bark and in vascular bundles of dicot stems and roots. They increase the diameter of stems and roots and the girth of the plant.
(iii) Intercalary meristems: They are located at the base of leaves or internodes. They increase the length of leaves and internodes.