Transpiration
Transpiration may be defined as the phenomenon of loss of water in the form of vapour from the internal tissues of aerial parts of plants under the influence of sunlight and regulated to some extent by the protoplasm.

Transpiration is very common in all land plants and takes place mainly through the stomata of leaves. Transpiration is not simple evaporation from the leaf surface but a phenomenon influenced and regulated by the living cells, according to the physiological necessity. Only a small amount of water absorbed by land plants is used in metabolic reactions. Most of the water absorbed by roots is lost by transpiration.