What are meristematic tissues? Explain with the help of suitable diagram. Give their classification on the basis of their position in the plant body.
Answers
Meristematic tissues are a group of young cells that are in a continuous state of division.
These tissues are mostly found at the apices of root and shoot.
The main characteristics of cells of meristematic tissues are:
(i) They are living and thin walled
(ii) Vacuoles are few and small in size
(iii) The cells contain a dense protoplasm and conspicuous nuclei
(iv) The cells are spherical, oval or polygonal in shape
(v) They do not store reserve food material and are in an active state of metabolism.
Classification on basis of position:
(i) Apical meristem:
These are found at the apices or growing points of root and shoot and bring about increase in length. It includes both pro-meristem as well as primary meristem.
(ii) Intercalary meristem:
It lies between the region of permanent tissues and is considered| as a part of primary meristem which has become detached due to formation of intermediate permanent tissues. It is found either at the base of leaf e.g. Pinus or at the base of internodes e.g. grasses.
(iii) Lateral Meristem:
These are arranged parallel to the sides of origin and normally divide periclinally or radially and give rise to secondary permanent tissues. These increase the thickness of the plant part.