英文摘要 |
Morphology and anatomy in root and leaf of Phalaenopsis amabilis were observed by microscope and TEM. The root has 2 ~ 3 layers velamen with lignified and suberized cell walls and one layer exodermis around the cortex. The mature velamen cells are vacuolated structures and pneumatodes are present in the velamen. The function of these structures is to enable gas exchange during the periods when the root is saturated with moisture. The V- shaped cells of the exodermis situated at the inner edge of the velamen develop secondary wall thickenings in the radial wall and outer tangential wall. The structure of exodermal cells are considered to play an important role in regulation of water absorption. The cortical cells store some starch grain in the cytoplasm and water in the large vacuole. The outer layes of the cortical cells contain more chloroplasts. The enodermis which form the innermost sheath of the cortex are continuous thick-walled cells. Whereas the thick-walled endodermis are constantly interrupted by the thin-walled passage cells, at the place where are exactly opposite to the phloem pole that is suggested to have relations with the nutrient and water transportation of cross section in the root. Phalaenopsis amabilis is CAM plant with thick leaves. The stomata densities of adaxial side and abaxial side in the leaf are 8.0 ~ 9.5/mm2 and 15.3 ~ 21.0/mm2, respectively. There are some protuberance from cuticle of the, epidermal surface. The outer cuticular ledges form at the outer cavity of stomata. These structures are protection and reduction in loss of water from the stomata and epidermis. There are some inter cellular space in the mesophyll that is beneficial to gas exchange. In the mesophyll cells, a large vacuole and chloroplasts are localized in the same cells. The chloroplast of mature leaf stores some starch grains and plastoglobuli, but in immature leaf, the chloroplast only stores plastoglobuli. |