Abstract: The peristome morphology of 16 species of the family Pottiaceae was observed by scanning electron microscope (SEM). The results show that the peristomes of these species are similar. They are haplolepideae. Peristome teeth are 1-3 sinistrorse circles or erect, basal membrane is present and densely covered with small papillae. While based on the differences of shape and rotation of peristome teeth and characteristics of basal membrane, three styles of peristome can be distinguished. It shows the hereditary differentiation of genus and species. This paper also discusses the adaptation of peristome morphology to the xerophytic environment.

Key words: Pottiaceae, Peristome, systematic significance, hereditary differentiation