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Transpiration is the evaporation of water vapour from plants cells to the atmosphere. It occurs chiefly through the leaves whiletheir stomata are open for the passage of carbon dioxide and oxygen during photosynthesis.

Transpiration also occurs through the cuticle and lenticels. Lenticels are pores in the stems ofwoody plants that allow gaseous exchange between the atmosphere and the internal tissues.

Transpiration is of immense importance in plant life as it is of great benefit to the plant. Thefollowing are the reasons why transpiration is important in plants. The significance of transpiration in plants includes:-

1. Cooling of the plant: The leaves absorb the radiant energy. Some of the light energy is utilized in photosynthesis. Therest is converted into heat energy resulting in an increase in leaf temperature. However, rapidloss of water in the form of water vapour from the aerial parts of the plant through transpirationbrings down their temperature. Transpiration thus provides a significant cooling effect whichkeeps the plant from being overheated.

2. Mineral transport;Mineral salts remain dissolved in the soil water and are absorbed by the roots. Minerals that arcabsorbed and accumulated in the xylem duct of the root move up and are distributed in the plantby the transpiration stream.

3. Water movement: The absorbed water is transported from roots to leaves through the xylem vessels. This is greatlyinfluenced by transpiration pull. Water loss due to transpiration results in the development of lowwater potential in the leaf tissues. Thus, water moves from the xylem vessels to the leaf cells.

4. Development of mechanical tissues: Greater amount of transpiration helps in the development of mechanical tissues in plants. Theplants become healthier and more compact, the cell walls become thick and cutinized and theplants are able to resist the attack of fungi and bacteria.

5. Maintenance of turgidity: Transpiration maintains an optimum degree of turgidity in cells. Under favourable conditions,plants absorb excess amount of water, which is given off by transpiration to maintain theoptimum turgidity for better growth.

6. Increase of taste of fruits: The solutes inside the cell become more concentrated when transpiration is rapid. Consequently,the concentration of sugar solution in the cells of fruits increases and fruits taste sweeter.

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