In plants, it is a thin layer of parenchyma found in roots, just outside the vascular cylinder. It regulates water flow. It consists of a single=celled ring which forms a selective barrier between the outer cortex and the inner pericycletissue. In the roots, the endodermis cells are impregnated suberin ,a waxy substance which is water resistant, to form a distinctive Casparian strips and prevent movement of water via the apoplast pathway. Water carrying mineral salts can only enter the root through the interior of cells (the symplast) as opposed to passing between cells (the apoplast). This means that the plant can directly regulate what enters the root proper. The endodermis cells contain starch granules as energy store. Mineral ions are activelt secreted into the xlem vessels to maintain root pressure.
