Ecoanatomical Study On Kobresia Willd. Of Eastern Qinghai-Tibet Plateau

Kobresia Willd. belongs to Caricoideae pax, Cyperaceae. There were about 70 species all over the world, among which there were 59 species and 4 variations in China. The genus were divided into 3 sections, which were section Kobresia, section Elyna and section Hemicarex (Flora of China, 2001). The thirteen species were selected for comparative anatomical study because of their broad distribution in eastern Qinghai-Tibet Plateau and their fitting to sampling with population.According to the results and discussion, the conclusion were as following:1. Five species named K. tibetica, K. littledalei, K. robusta, K. pygmae and K. vidua have adaxial and converged mesophyll parenchyma. Among them, K. tibetica, K. littledalei and K. robusta belong to section Elyna, K. pygmae and K. vidua belong to section Hemicarex. In section Elyna, K. setchwanensis, K. capilifolia and K. humilis and in section Hemicarex, the parenchyma of K. graminifolia shaped air cavity which arraied between vascular bundles.2. Seven species named K. cuneata, K. myosuroides, K. tibetica, K. robusta, K. littledalei, K. pygmae and K. vidua have only abaxial palisade tissue. Among them, K. cuneata, K. myosuroides, K. tibetica, K. robusta, K. littledalei belong to section Elyna, K. pygmae and K. vidua belong to section Hemicarex. But, the palisade tissues of K. setchwanensis, K. capili folia and K. humilis of section Elyna, and K. gramini folia of section Hemicarex distributed in both epidermis.3. Four species named K. kansuensis, K. cuneata, K. setchwanensis and K. robusta have contiguous or discontiguous hypoderm. Besides, K. kansuensis belongs to section Kobresia, K. cuneata, K. setchwanensis and K. robusta belong to section Elyna. Other species were no hypoderm.4. In section Hemicarex, the outline of transverse sections of K. pygmae and K. vidua were not "V" shape, the keels of lower epiderms were not extruded and the grooves of upper epidermis were straight. The outline of transverse section of K. graminifolia was "V" shape, the parenchyma formed air cavity and arraied between vascular bundles, palisade tissues distributed on both epidermis, the keels of lower epidermis were extruded and the grooves of upper epidermis were expanse and shallow. 5. According to the clustering analysis, K. royleana and K.kansuensis of Sect. Kobresia, K. setchwanesnsis,K. capilifolia and K. humilis of Sect. Elyna and K. graminifolia of Sect. Hemicarex were in the same group. K. cuneata,K. myosuraides,K. tibetica,K. littledalei and K. robusta of Section Elyna and K. pyrmae and K. vidua of Section Hemicarex were in the same group.6. There are mutual characteristics for 13 species of Kobresia Willd. With other species of Cyperaceae in the types and array of stomatal apparatus, the shapes of epidermal cells and the types of vascular bundles;with other species of Carex in the following characteristics: adaxial epidermal cells bigger than abaxial ones, mesophyll cholrenchyma not radial array, well developed air cavities between vascular bundles, well developed bulliform cells. The characters of transverse section and epidermal anatomal characters of leaves differ from each other to certain degree, which are as follows. At transverse section,they are different from outline, abaxial keels and adaxial grooves, papillaes or not, the distribution and layers of palisade tissue, the size and shape of air cavities, the shape and number of bulliform cells, array mode of mesophyll parenchyma. At leaves epidermis,types of cells, shapes of anticlinal walls, types of papillaes and silica bodies also vary among species. Moreover, K. cuneata , K. myosuroides, K. tibetica, K. littledalei, K. robusta, K.pygmae and K. vidua are similar to each other in structure, nevertheless, are greatly different to other species.7. Along altitude, anatomical structures of K. hulimis varied, including the thickness of leaves, epidermis etc.