Question

Write briefly on : Hydathode cuticle transpiration - stomatal transpiration - lenticular transpiration

Answer 1

Transpiration is the process in which plants release water present in it in the form of water vapour.

Hydathode cuticle transpiration

• The cuticle is an impermeable, waxy or resinous layer of cutin covering the epidermis of leaves and stems of plants.
• A hydathode is a pore found in the epidermis of the leaves of certain plants.
• Cuticular transpiration is the loss of water in the form of vapour in plants through the cuticle.
• Water vapour diffuses through the cuticle on leaves and escapes to the atmosphere.
• Cuticular transpiration continues throughout day and night.
• 5-10% of water is given out through this transpiration.
• This type of transpiration depends on the thickness of cuticle present in plants.

Stomatal transpiration

• The tiny pores present on the under surface of plant leaves are known as stomata.
• Stomatal transpiration is the diffusion of water vapour through the stomata.
• This is the most important type of transpiration.
• The stomata expose the wet interior of the plant to the atmosphere. The internal air becomes saturated with water vapour. The outside air is seldom saturated with water.
• Therefore water vapour pass outwardly through stomata by diffusion.
• This takes plants in the presence of sunlight as stomata remains opened only in the presence of sunlight.
• 80-90% of water is lost through this type.
• This continues till the stomata remain opened.

Lenticular transpiration

• ​​​​​​Water may also evaporate through certain other openings present on older stems. These openings are known as lenticels.
• The transpiration that occurs through such openings are known as lenticular transpiration.
• Only 0.1% of water is lost in this type of transpiration.