Question

Name the three types of transpiration. Which of these account for maximum transpiration in the plant?

Answer 1

There are three types of transpiration which are as follows:

1. Stomatal transpiration:

1. The leaves have minute pores guarded by two bean-shaped guard cells. These are called stomata.
2. Stomatal transpiration occurs from leaves through minute pores in leaves called stomata.
3. Maximum transpiration takes place through stomata.
4. About 90% of total transpiration takes place through stomata.

2. Cuticular transpiration:

1. To minimise water loss by transpiration, the epidermis of the leaves secrete a thin layer of wax coating called the cuticle.
2. The thicker the cuticle, the lower the rate of transpiration.
3. However, water loss may take place from the thin cuticle layer and contributes to cuticular transpiration.
4. About 10% of total transpiration takes place through the cuticle.

3. Lenticular transpiration:

1. Lenticels are special openings that develop in older and woody parts of the plant in place of stomata.
2. water from the cell surface directly facing the lenticel evaporates and contributes to lenticular transpiration.
3. Lenticels never close, they remain open all the time but the amount of transpiration through lenticels is very less compared to stomatal transpiration.

Percentage contribution of each type of transpiration in total transpiration.

1. Stomatal transpiration: 85-90%
2. Cuticular transpiration: 8-10%
3. Lenticular transpiration: 0.1-1 %

Therefore, stomatal transpiration contributes to maximum transpiration in the plant.