What is the function of the endodermis in plants?

The endodermis serves as a critical boundary layer in the plant root system, specifically functioning to control the movement of water, nutrients, and other substances between the cortex of the root and the inner vascular system. It is the innermost layer of the cortex and is characterized by the presence of a Casparian strip, a band of suberin that acts as a waterproof barrier. This characteristic of the endodermis ensures that all water and solutes must pass through the cell membranes of the endodermal cells, allowing the plant to selectively absorb minerals and prevent unwanted materials from entering the vascular system. This selective permeability is essential for maintaining the plant's homeostasis and overall health, ensuring it receives the nutrients it needs while blocking harmful substances.