The Turgescence is the cellular state associated with the elongation of the vegetable cell, caused by a water entry in this same cell. Water having become abundant in the vacuole, the pressure exerted of the interior of the cell about the middle operates then on the primary wall. This phenomenon is called pressure of turgescence .

The water entry itself is caused by the phenomenon of the Osmose, according to which two mediums of concentrations different and separated by a semipermeable membrane (letting pass the dissolved water but not substances) operate an exchange: the water of the medium less concentrated crosses the wall to restore the balance of the concentrations.

When water enters the vegetable cell, the vacuole fills and grows bigger and its membranes are tightened. One will speak then about turgescence of the cells. The water of the cells exerts a pressure on their wall and give rigidity to the flexible parts of the plant (stem, sheet, starts-up,…). If the cells empty water, turgescence ceases, the vacuoles retract, the cytoplasmic membranes fall apart of the Paroi, the genitals of the plant are softened and the latter fades.

See also the opposite process: Plasmolysis