A Diffusion Barrier (IMAGE) Nagoya University Caption Vascular plants have evolved a physical barrier that prevents passive apoplastic diffusion of ions and water across the endodermal cells that surround the vascular bundles. This hydrophobic barrier embedded within the walls of endodermal cells is called the Casparian strip. Credit Yoshikatsu Matsubayashi Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.