Thus, favoring the movement of water into the stele so that the root is acting like an osmometer and the water that enters the stele is pushed up the xylem of the stele as more and more water enters the stele. This mechanism is called root pressure. Root pressure can move water up through a plant about 3 meters. If a plant takes more water than it can use by root pressure, it will sometimes drip out the end of a leaf in process known as Guttation. This happens in short plants only.
Transpiration is term given to the loss of water from the shoot of the plant.
When the stomas are open and the exchange of carbon dioxide and oxygen is taking place, water can also evaporate from the moist tissues of the leaf into the air. If a plant loses more water than it can replace - the plant has a water deficit and water is then lost from its cells and their vacuoles. When the plant's cells lose water they can be come flaccid or limp. When a plant loses more water by tranpiration than it can replace, the stoma will close slowing or stopping further water loss. When guard cells are turgid, they have a hydrostatic pressure that causes them to swell and bow apart opening the stoma.