Transpiration is the major way by which plants loose water (95%).
It occurs through the stomata. Water loss is essential for plants because it
releases the pressure, aids continuous intake of water by the plant, and allows
the water to move to other parts of the plant that need water. Water loss
through transpiration is regulated by Guard cells, which help prevent plants
from drying out by regulating the opening & closing of the stomata, thus
regulating the flow of the water vapor from the leaf tissue.
