Stomata

Stomata, minute openings in the epidermis of leaves and tender green stems of plants, and subserve the purpose of respiration (see VEGETABLE PHYSIOLOGY). They are found in parts exposed to sun and light, and hence are most numerous on the upper surface in most leaves, on the under side of floating leaves, but in some monocotyledons equally distributed. See illustration at LEAF; and for the complex stomata of Marchantia, see LIVERWORTS.