Question

In broad leaf why is stomata only present on the lower side?

Answer 1

​Stomata:

1. Stomata are the tiny openings present on the epidermis of leaves.
2. We can see stomata under the light microscope.
3. Stomata play an important role in gaseous exchange and photosynthesis.
4. They also control the transpiration rate by opening and closing of their guard cells.
5. The amount of light affects the opening and closing of the stomatal pore.
6. Light stimulate the opening of the stomata leading to more transpiration.
7. The speedy wind also increases the rate of transpiration through stomatas.

Reason for stomata on lower surface of leaf:

1. This is an adaptation to prevent excess water loss.
2. Broad leaves are held horizontally and hence upper surface is directly illuminated.
3. The stomata must get open during the daylight hours to let oxygen and carbon dioxide pass through.
4. While they are open, water vapour also escapes into the atmosphere (transpiration).
5. But there won’t be direct exposure to the sun if the stomata are present at the lower surface of the plant and they will be more protected from the breeze.
6. Transpiration is the loss of water through stomata, so, more stomata are found on the lower surface to prevent excessive loss of water.