Plants absorb water through tiny hairs that cover the surface of the roots. Water is absorbed by osmosis — the movement of water molecules through a semipermeable membrane from an area of high concentration to an area of low concentration. Transpiration, the release of water vapor through the leaves, is the main force that controls the movement of water through a plant. Transpiration is regulated by the stomata, tiny pores on the underside of leaves that open and close to release water vapor and exchange carbon dioxide and oxygen. When the plant’s water concentration is high, the stomata open to release excess water; when the water level drops, the stomata close to conserve moisture.
