Stomata are tiny plant structures found on the outer skin layer, also known as the epidermis, of plants. They consist of two specialized cells, called guard cells that surround a tiny pore called a stoma. They allow communication between the internal and external environments of the plant. Their main function is to allow gases suh 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 herbaceous stems and leaves. They are formed during the initial stages of the development of these various plant organs and therefore reflect the environmental conditions under which they grew.