Characters of leaf epidermis and systematic research in Pleurospermum from China.

Epidermal characters of mature leaves in 11 species of Pleurospermum were investigated under both light microscope(LM) and scanning electron microscope(SEM).It was shown that the stomata were anomocytic and existed in abaxial epidermis in all the species examined,and in the adaxial epidermis in some species.The leaf epidermal cells were usually irregular or polygonal in shape.The patterns of anticlinal walls were slightly straight,straight-arched,sinuolate or sinuous.Under SEM,the inner margin of the outer stomatal rim was nearly smooth,sinuolate or sinuous,and the cuticular membrane of the leaf epidermis was stripe,sometimes stripe apophysis,occasionally granules,druse.Stomatal and other epidermal features can be used for distinguishing some species.In the light of our studies both on micromorpha and external morpha,we suggest retaining P.prattii and P.wrightianum as separate species and P.franchetianum and P.davidii are closed related.