Abstract: The leaf epidermises of 15 species of Leymus were examined under the light microscope.It was found that these micromorphological differences shown by the lower epidermis may be applied to dividing the Chinese Leymus species into three groups.And in accordance with the external characteristics of each group, these three groups should separately belong to sect.Leymus, sect.Aphanoneuron and sect.Anisopyrum which were described by our predecessors.Moreover, according to the variation trends of leaf epidermal characters, the relationships among three Chinese sections were analysed as well.The results show that sect.Leymus is the most primitive and sect.Anisopyrum is the most advanced among three sections, whereas sect.Aphanoneuron lies between the above two sections;sect.Anisopyrum shows direct relationship with sect.Aphanoneuron, but indirect relationship with sect.Leymus.

Key words: Leymus, leaf epidermis, classification of sections, relationships among the sections, China