Stomata are tiny pores, and composed of two bean shaped epidermal cells called guard cells which enclose stomatal pore. Stomata are mostly present in epidermal layers of leaves and in other aerial parts like young stems, floral parts etc. Guard cells in dicots are kidney shaped and in monocots are dumb bell shaped. The guard cells may be surrounded by varying number of specialized epidermal cells called subsidiary cells or accessory cells.
