Casparian Strips Occur In

Casparian strips occur in the endodermis of plant roots.

Explanation:
Casparian strips are band-like thickenings made of suberin and lignin, present in the radial and transverse walls of endodermal cells. They act as a barrier to passive flow of substances like water and minerals into the vascular cylinder (stele) of roots.

• They force water and solutes to pass through the cytoplasm of endodermal cells via the symplastic route, instead of moving freely through cell walls (apoplastic pathway).

• This regulates and filters what enters the xylem, providing the plant with a controlled uptake mechanism.