Stomata
Stomata are microscopic structures on plants found typically on the outer leaf epidermis. They consist of two specialized cells, called guard cells that surround a tiny pore called a stoma. The word stomata means mouth in Greek because they allow communication between the internal and external environments of the plant. Their main function is to allow gases such as carbon dioxide, water vapour and oxygen to move rapidly into and out of the leaf. Stomata are found on all above-ground parts of plants, including the petals of flowers, petioles, soft stems and leaves. They are formed during the initial stages of the development of these various plant organs and reflect the environmental conditions under which they grew.