气孔(器)（Stoma (organ)）.docVIP

气孔(器)（Stoma (organ)） Stoma (organ) The two specialized cells on the plant epidermis - the general term for the guard cell and the openings (pores) formed by it. Stomata are the main gateway for plants to exchange gases with the outside world. In some plants, there are also one or more sub cells in the stoma that are different in shape from those of normal epidermal cells. The accessory cells often have a certain arrangement. Stomata are found in organs of the upper part of the vascular plant and on the leaves. Some bryophytes also have stomata, such as moss moss. Most of the guard cells of dicotyledonous plants are in the shape of the kidney, whereas most of them are dumbbell shaped. The number and distribution of stomata, the number and the distribution of the leaf area per unit, vary with species. Some plants on leaf epidermis and lower epidermis of leaf had lower epidermis but more; some plants only in the lower epidermis stomata; a few leaves floating in the water, such as water lily, stomatal occurred only in the upper epidermis; local area epidermis of some plant stomata only distributed in leaf, such as oleander. Leaves of submerged plants usually have no stomata. The distribution of stomata is related to environment. Many lower leaves of the leaf have more or more stomata on the lower epidermis, which is adapted to the arid environment. Stomatal category according to the position between the hole and the adjacent cells, the stomata of dicotyledonous plants are divided into 4 types: irregular type, a few cells surrounded by guard cells, these cells in morphology and size and other epidermal cells, Ranunculaceae, Cucurbitaceae and Scrophulariaceae plant belong to this type; the range of cell types, the guard cells are surrounded by 3 different size subsidiarycells. As of Cruciferae, Solanum and Sedum plants; the paracytic, each outside of guard cells have one or several subsidiary cells, subsidiarycells parallel to the long axis of the guard cell and the long