Transpiration is necessary evil. Explain?

Explanation

Transpiration has both beneficial and harmful effects. They are Beneficial effects : (1) It helps in passive absorption of water. (2) It also helps in passive absorption of mineral salts by Mass flow mechanism. (3) It is the main force for ascent of sap. (4) It regulates the temperature of plant body and provides cooling effect.
Harmful effects : (1) Excessive transpiration makes the cells flaccid which retards growth. (2) Excessive transpiration leads to closure of stomata thus obstructing gaseous exchange.
Hence transpiration is considered to be a necessary evil.