What is one key function of the endodermis in plant roots?

One key function of the endodermis in plant roots is to regulate water and nutrient uptake. The endodermis acts as a selective barrier that controls the movement of water and dissolved substances from the soil into the vascular system of the plant. This layer is characterized by the presence of the Casparian strip, which is a waxy band of suberin that encircles the endodermal cells. This structure prevents passive flow of materials and forces water and solutes to pass through cell membranes, where they can be selectively absorbed or excluded according to the plant's needs. Thus, the endodermis plays a critical role in ensuring that the plant takes in only the necessary nutrients and maintains homeostasis, optimizing its growth and development.