What is meant by meristematic tissues ? Explain its various types.

$\rightarrow$ Growth in plants is largely restricted to specialised regions of active cell division called meristems.

$\rightarrow$ Plants have different kinds of meristems. They are as follow.

$(A)$ Apical Meristems: The meristems which occur at the tips of roots and shoots and produce, primary tissues are called apical meristems.

$\rightarrow$ Root apical meristem occupies the tip of a root while the shoot apical meristem occupies the distant most region of the stem axis.

$\rightarrow$ During the formation of leaves and elongation of stem, some cells 'left behind' from shoot apical meristem, constitute the axillary bud. Such buds are present in the axils of leaves and are capable of forming a branch or a flower.

$(B)$ Intercalary Meristem : The meristem which occurs between mature tissues is known as intercalary meristem. They occur in grasses and regenerate parts removed by the grazing herbivores.

Both apical meristems and intercalary meristems are primary meristems because they appear early in life of a plant and contribute to the formation of the primary plant body.

$(C)$ Lateral Meristem : The meristem that occurs in the mature regions of roots and shoots of many plants, particularly those that produce woody axis and appear later than primary meristem is called the secondary or lateral meristem.

$\rightarrow$ They are cylindrical meristems. Fascicular vascular cambium, interfascicular cambium and corkcambium are examples of lateral meristems. These are responsible for producing the secondary tissues,