The loss of water in the form of vapors from the aerial parts of the plant is called Transpiration.
- It takes place mainly through Stomata.
- The water which is lost through the stomata is replaced by water from the xylem vessels in the leaf.
- Evaporation of water molecules from leaf ‘s cells creates a suction (transpiration pull) which pulls water from the xylem cells of the root.
Why is Transpiration Important for Plants
- Creating suction force
- Distributing water.
- It helps in the regulation of temperature.
- Evaporation reduces the temperature of leaf surface.
- Therefore, transpiration is useful to plants on hot sunny days. (At intense heat, the enzymes are destroyed).
- Transpiration helps in the ascent of sap by producing a suction force acting from the top of a plant.
- Evaporation from the leaves concentrates cell sap and increases their osmotic pressure.
- This draws water from the cells at the lower levels in a sequential manner (ascent of sap) and finally favors absorption of water from the soil by the roots.
- As the water evaporates from the leaves, a suction force is produced at the top of the plant drawing more water up through the stem and making the roots absorb more of it from the soil.
- Transpiration helps in the absorption and upward movement of water and minerals dissolved in it from roots to the leaves.
Distribution of water and mineral salts
- Since leaves are present at the tips of all branches and twigs, transpiration from their surfaces
- tends to draw water towards them and thus helps in the distribution of water throughout the plant body.
- Transpiration maintains a constant supply of ions to the leaves.
- Higher the rate of transpiration, greater the rate of absorption of water and solutes from the soil.
- Transpiration also removes excess water from the plant