Transpiration is of following three types:
1. Stomatal transpiration
2. Cuticular transpiration
3. Lenticular transpiration
1. Stomatal transpiration:
Stomata are minute openings found in the epidermis of leaves and on herbaceous stems. About 90-97% of total water, absorbed by plants is lost through these openings.
2. Cuticular transpiration:
A waxy coating found on the surface of the outer wall of epidermal cells of aerial parts of plants is called cuticle.
- When loss of water occurs from the surface of leaves and herbaceous stem by direct evaporation from the epidermal cells through the cuticle, the process is called cuticular transpiration.
- The amount of water lost through cuticle is very low and varies with the thickness of cuticle and accounts only 3 to 10% of the total water loss.
- In xerophytes, a very thick cuticle is found as an adaptation to reduce cuticular transpiration.
- Transpiration from the surface of herbaceous stems, fruits and floral parts is mostly cuticular.
- Cuticular transpiration takes place continuously during day and night.
3. Lenticular transpiration:
Lenticels are the minute areas found in the bark of woody stem and the fruits. These are filled with loosely arranged cells known as complementary cells.
- Loss of water from lenticels is called lenticular transpiration.
- Lenticular transpiration is negligible and accounts for only 0.1% of the total water loss.
- This also occurs continuously during day and night.