Endodermis

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Endodermis is the bottom layer of skin.

In plants, it is a thin layer of parenchyma found in roots, just outside the vascular cylinder. It regulates water flow. Endodermis is tightly packed together and contains Casparian strips on their anticlinal (radial and transverse, i.e. perpendicular to the root's surface) walls which are made of suberin mainly, a waxy substance which is water resistant. Water 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.