Stomata are pores in the epidermis of a plants leaf that allow for the expulsion of gas, and are protected by two curved guard cells. If the environment around the plant is hot and dry the guard cells will shrink and cause the stomata to close to conserve excess water, when there is a large amount of moisture the guard cells will absorb the water and become turgid. And the stoma are found on the underside of the leaf to minimize water loss