casparian strip
Diagram of symplastic and apoplastic water uptake by a plant root. The Casparian strip forces water into the symplast at the root endodermal cells.
A casparian strip is a waxy, waterproof band of a material called suberin found in the walls of plant root cells. Named after the 19th century German botanist Robert Caspary, the casparian strip prevents the diffusion of water and minerals into the main vascular system of the root.