Transpiratin is loss of water in vapour form from the exposed parts of a plant. There are three types of transpiration - lenticular, cuticular and stomatal. Lenticular transpiration
is the loss of water in vapour form from lenticels present in the bark by stems. It is only 0.1% of the total. Cuticular transpiration
is loss of water in vapour form through the cuticular covering of the leaves and other aerial parts. Amount of cuticular transpiration depends upon the thickness. Stomatal transpiration
is loss of water vapours through stomata present over leaves and other soft aerial parts. It will always occur whenever stomata are open for gaseous exchange.