It is the ability of a plant to maintain favorable water balance and turgidity even exposed to draught conditions there by avoiding stress and its consequences. Stress avoidance due to morphological, anatomical characteristics which themselves are the consequences of the physiological processes induced by drought these zerophytic characteristics are quantitative a d vary according to environmental conditions.

A favorable water balance under drought conditions can be achieved by transpiration before a• soon as stress is experienced. These are called “water savers” or Accelerating water uptake sufficiently so as to replenish the lost water called as “water spenders”