What are the types of transpiration?

Explanation

Types of Transpiration: Transpiration is of following three types:
I. Stomatal transpiration: Stomata are microscopic structures present in high number on the lower epidermis of leaves. This is the most dominant form of transpiration and being responsible for most of the water loss (90 - 95%) in plants.
2. Lenticular transpiration: In stems of woody plants and trees, the epidermis is replaced by periderm because of secondary growth. In order to provide gaseous exchange between the living cells and outer atmosphere. some pores which looks like lens-shaped raised spots are present on the surface of the stem called Lenticels. The loss of water from lenticels is very insignificant as it amounts to only 0.1 % of the total.
3. Cuticular transpiration: The cuticle is a waxy or resinous layer of cutin, a fatty substance covering the epidermis of leaves and other plant parts. Loss of water through cuticle is relatively small and it is only about 5 to 10 % of the total transpiration. The thickness of cuticle increases in xerophytes and transpiration is very much reduced or totally absent.
OR
Phytochrome is a bluish biliprotein pigment responsible for the perception of light in photo physiological process. Butler et al.., ( 1959) named this pigment and it exists in two interconvertible forms: (i) red light absorbing pigment which is designated as `P_r` and (ii) far red light absorbing pigment which is designated as `P_fr`. The `P_r` form absorbs red light in 660 nm and changes to `P_fr`. The `P_fr` fom1 absorbs far red light in 730 nm and changes to `P_r`. The `P_r` fom1 is biologically inactive and it is stable whereas `P_fr` form is biologically active and it is very unstable. ln short day plants. `P_r` promotes flowering and `P_fr` inhibits the flowering whereas in long day plants flowering is promoted by `P_fr` and inhibited by `P_r` form. `P_fr` is always associated with hydrophobic area of membrane systems while `P_r` is found in diffused state in the cytoplasm. The interconversion of the two forms of phytochrome is mainly involved in flower induction and also additionally plays a role in seed germination and changes in membrane conformation.