On a sunny day our body temperature tends to rise, the sensors on our body tells our brain to induce sweat but we cool off easily by losing 1-2% body fluid. Plants on the other hand lose gallons of water everyday, upto 99% water absorbed from roots is lost through evapotranspiration. You may now wonder why plants have not evolved to prevent such loss of water. Actually, some already have such as cacti! Other plants, however, continue to transpire because of the benefits. Evap