A Taxonomic Study On The Mongolian Plateau Of Mongolian Plateau

Didymodon, belonging to Musci Bryales Pottiaceae, is the most important components in the temperate mountain. It can be distinguished from Barbula based on its morphologic characteristics. However, what is under controversy is whether Didymodon is a natural group by the lack of unique feature. There are various Didymodon in Mongolian plateau, but the research between Chinese and Mongolian scholars in such species has been relative independent and lacked system for a long time. Therefore, Mongolian plateau cannot be regarded as the geographic and ecological units to do some further comprehensive research.We divided the species of Didymodon in this area into two sections, that is, Sect. Fallaces and Sect. Didymodon according to the classification system of Zander. This research is based on the specimen in HICM, UBA and some other domestic and overseas museums. By rearranging these statistics, the conclusions can be drawn as follows:Firstly, the definition of Fallace and Didymodon is confirmed and the obvious feature is upper and middle cells, rectangle or short-rectangle, the transverse section of costa with main cells in 1 layer, and ventral stereid. Leaves are integrated with stems when they are dry; however, they will erect against one another when they are humid.Secondly, the type of the expansion, shape, cells and warts of leaves plays an important role in the taxonomy of different species and genus.Thirdly, this paper confirms that there are 9 species and 1 variation through the taxonomy of Sect. Fallaces, namely, Didymodon asperifolius, D. constrictus, D. constrictus var. flexicuspis, D. ferrugineus, D. giganteus, D. fallax, D. johansenii, D. leskeoides, D. tophaceus and D. zanderi respectively.