Significance of Transpiration

Transpiration causes a plant to lose water on a genuinely large scale - roughly 95% of everything a plant absorbs through its roots is eventually lost again as transpired vapour - which on the surface looks like a wasteful, even harmful process for the plant to run. But several other essential processes depend directly on transpiration to function at all: passive water absorption from the soil, the ascent of sap up through the xylem, and mineral absorption are all driven, in large part, by the pull that transpiration generates. Transpiration also plays a genuinely protective role, helping the plant withstand the stress of strong, scorching sunlight by evaporatively cooling its tissues. It is precisely this two-sided character - a large, seemingly wasteful loss of water that is nonetheless indispen …