What are Casparian strips?

Explanation

i. The radial and the inner tangential walls of endodermal cells are thickened with suberin and lignin in roots.
ii. This thickening was first noted by Casparay. So these thickenings are called casparian strips.
iii. Casparian strips are absent in the endodermal cells which are located opposite the protoxylem elements .