Question

What is the role of stomata in transpiration?

Answer 1

Since most of the water (90%) is lost through stomata, plants regulate the degree of stomatal opening to reduce the water loss. Provided that the plant has an adequate supply of water, the water which is lost through the stomata is replaced by water from the xylem vessels in the leaf. During the day when the stomata are open, the transpiration pull becomes the major driving force in the movement of water in the xylem.