(a) : The root system of a plant develops from the hypocotyl of the embryo of a seed. The root shows following four regions these usually merge into one another, without distinct boundaries between them.
The zones, successively from the apex to the base are- (i) Root cap zone : The apex of each root is covered by a cushion of thin walled cells known as root cap. (ii) Region of cell division : It lies just behind the root cap. It is the main growing region of the root where active cell divisions take place. (iii) Region of elongation : The region of elongation is responsible for growth in length of the root. (iv) Region of maturation : Epidermal cells of this region give out small, thin, cylindrical unicellular outgrowths, known as root hairs. These are the main absorbing organs of the root.