Stomata

Openings in the outer surface of a plant. Stomata are pores that are particularly present in the upper surface (which is also called the epidermis) of a grass leaf. These pores are enclosed by what are called guard cells, which control the opening and closing of the pores. Stomata allow for the exchange and transfer of gases and water vapour: Carbon dioxide into the plant and Oxygen out of the plant as part of the process of photosynthesis; and transfer out of the plant of Carbon dioxide and Water as part of the process of respiration. A single pore is called a Stoma.