Significance of Transpiration:

Transpiration is called a necessary evil. It means that transpiration is a potentially harmful process but is unavoidable too.

1. Transpiration may be a harmful process in the sense that it There is strong and requires wet surfaces from which evaporation can occur evidence that even during the conditions of drought loss of water from the plant mild water stress results in wilting, serious desiccation, and often the death of the plant, results in reduced This is the reason that at high temperatures, plants close their growth rate, stomata and reduce transpiration rate to prevent wilting.
2. On the other hand, transpiration is necessary too. It creates a pulling force called transpirational pull which is principally responsible for the conduction of water and salts from roots to the aerial parts of the plant body. When water transpires from the surfaces of the plant, it leaves a cooling effect on the plant. This is especially important in warmer environments. Moreover, the wet surfaces of leave cells allow gaseous exchange.

Note:

There is strong evidence that even mild water stress results in a reduced growth rate.