Why the endodermal cells possess casparian strips in their radial and transverse walls ?

Explanation

Casparian strips are made up of waxy substances (like suberin etc) which do not allow solute and solvent molecules to pass through it. The ions rriove only through the living protoplast of endoderrrial cells. The differentially permeable plasma membrane greatly retards free diffusion of ions and, therefore, prevents a rapid loss of ions from the xylem. Moreover, the endodermis forrns a water-tight j2cket around the vascular cylinder and helps to maintain the root pressure