The condition that arises in plants when more water is lost by evaporation than is absorbed from the soil. This causes the cells to lose their turgor and the plant structure droops. The plant hormone abscisic acid (ABA) accumulates in leaves and signals the guard cells to close leaf pores (stomata) and reduce the loss of water vapour. Plants can normally recover from wilting if water is added to the soil, but permanent wilting and possible death can result if the plant does not have access to water for a long period of time. In certain plants wilting is important as a mechanism to avoid overheating: when the leaves droop they are taken out of direct contact with the sun’s rays. When the sun sets the plant can begin to transpire at the normal rate and the cells of the leaves regain their turgor.