Cortex

part of the primary structure of the root or stem that lies between the skin and the middle column. The cortical layer is mainly composed of loosely arranged multi-layer thin-walled cells, which contain other
tissue
components, such as fibers, thick horn cells, secretion cells, stone cells, etc. The cortical layer mainly protects, supports, stores and so on. The cortical cells of young stems tend to contain leafy greens, which are feasible for photogenic use. After the roots or stems of the woody plant grow thicken in secondary life, the cortical layer of the root falls off or is crushed due to the formation and activity of the wood hydrant formation layer, and the cortical layer of the stem declines. The innerst layer of the root cortical layer of cells is the endotrial layer, the cells are arranged tightly, no cell gap, its radial wall and lateral wall with a bolted ribbon thickening, called the Kye belt. General stems have no endoders, only sunk plants (such as eye vegetables) stems or some underground stems have Kels band thickening.