Abstract: The paper aimed to figure out the taxonomic values of the peristomial structure and spore morphology in Bryum,and also to discuss the relationship between the natural environmental conditions and the diversity of Bryum at the Altun Mountain National Nature Reserve in Xinjiang. Morphological characters of peristome and spores from 18 species of the genus Bryum in the area were observed by the scanning electronic microscope (SEM).The results showed that: ① The characters,such as the exostomium teeth shape,pattern of exostomium dorsal surface,width of perforation on the endostomium segments,length of the endostomum basal membrane,development of cilia and exine ornamentation of spore,were different among the taxa in Bryum,and they were stable for each species in the genus.So their presence is often considered to be highly diagnostic and taxonomical in infrageneric classification combining with other sporophyte characteristics and/or gametophyte characteristics;② When the peristome developed most highly (the so-called perfect peristome),it was consisted of the longer exostome teeth,a high endostomium basal membrane,broad segments and appendiculate cilia.Otherwise,less intricate peristomes (the so-called simpler peristome) of some Bryum species had shorter exostome teeth,lower endostomium basal membrane,narrower segments and shorter and fewer cilia or absent;③ It seems that the rich diversity of Bryum in the Altun Mountain National Nature Reserve is related to the peristomium structure and spore morphology being adaptive for spore dispersing in dry environment.

Key words: Bryum, peristomium structure, spore exine ornamentation, SEM, the Altun Mountain National Nature Reserve, Xinjiang