Root: The root is non-green, cylindrical descending part of the plant that normally grows downwards into the soil. A typical root possesses five parts or regions :
1.Root Cap : It is a thimble shaped or cap like,structure present at the tip of the root. The cells of root cap secrete mucilage, which lubricates the passage of root through the soil. The cells also possess starch grains which are responsible for perception of gravity.
2.Growing or meristematic zone: It lies partly within and partly beyond the root cap. The cells of this zone divide actively and add new cells to root and root cap.
3.Zone of Elongation: It lies behind the meristematic zone. The cells of this region are newly formed cells,which lose the power of division. These also possess the power of absorption of water from the soil.
4.Zone of Root hair : It lies above the region of elongation and bears a clusters of very fine tubular outgrowths called root hairs. This zone is also called the zone of differentiation because different types of primary tissues mature in this region.
5. Zone of Maturation : This region forms the major part of the root and no change occur in this region. It forms the permanent zone of the root and also gives out lateral roots.