Water is transported from the roots, where the main portion of water is absorbed, and up the plant through the xylem; the xylem is an interconnected system of tubes where the water circulates through the plant. Water then flows through the cortex of the plant, through the endodermis, or innermost layer of cells, and finally into the cells' vascular bundles. Transpiration, which is the evaporation of water through the stomata, is responsible for the movement of the water from the xylem into the mesophyll cells and finally into the leaves.