Most of the water absorbed is lost through the ariel parts of plants into the air by the processes called transpiration. Very little water (less than2%) is used in various metabolic activities of plants. Most of the transpiration takes place through leaves known as foliar transpiration.
Types of transpiration
Transpiration may occur through the cuticle, lenticels, stomata, and sometimes bark, and according It is called. cuticular, lenticular, stomatal, and bark transpiration.
- Cuticular Transpiration: It is the loss of water in vapor from the general surface (leaves and young stems) through the layer of the cuticle. Cubicula transpiration is appreciable only in case the cuticle is thin as in entophytic plants growing in humid areas. It continues throughout the day and night.
- Stomata Transpiration: It is the loss of water in vapor from the stomata present on the surface of leaves and to lesser on the surface of leaves and to the lesser extent on the surface of flowers and young stem. It is the major part of transpiration (80-90%) it, however, occurs only when stomata are open.
- Lenticular Transpiration: This is the loss of water in vapor from lenticels or aerating poxes present in the bank of the stem.
- Bark Transpiration: A small quantity of water is lost from the corky bark of the stem. Both lenticular and bark transpiration continues day and night time.