Abstract:Peristome morphology of 12 species of the genus Bryum Hedw. were observed by LM and SEM. The results show that based on the tropism of dentium the 12 species could be divided into three types: approximately erection; dentium insert between two processus; excurvature of dentium. According to cilia of the genus the 12 species may also be divided into three groups. Meanwhile, the clustering analysis and principal components analysis of these species have been made by the software STATISTICA 6.0. The result showed that the dentium charactenstics, like tropism of dentium and the development state of cilia, can be the standards to classify the plants in Bryum among species. The paper gives new information on the system evolution study on the characteristics of moss peristome.