Why does transpiration occur mainly through leaves other than other parts of a plant?

Transpiration is the process by which plants lose water vapour through their aerial part. It may occur through leaves, green stems and lenticels of woody stems, but 90%occur through the leaves.

Explanation

• Leaves are numerous and so offer a larger surface area for escape of water vapor by diffusion from plants.
• Leaves are thin to easy evaporation of water
• Leaves contain numerous pores (stomata) through which a large amount of water vapour can escape
• The spongy mesophyll cells have large intercellular spaces in which water can easily evaporate from neighboring cells to enhance its exit as water vapour from the plants. There are no such intercellular spaces in the other plant parts.
• Leaves are covered with a thinner cuticle which offers less resistance to the escape of water
• Being at the terminal point of the transpiration pull, leaves lose more water to enhance its uptake from the soil and its distribution to the rest of the plant.