For finding valuable systematic characters, leaf epidermis of 77 taxa, representing 12 sections of the genus Clematis and three related genera in the Ranunculaceae, were examined mainly by means of light microscopy (LM), and partially by scanning electron microscopy (SEM). It was shown that the leaf epidermal cells were usually irregular or polygonal in shape. The patterns of anticlinal walls were straight, arched or undulate. The stomatal apparatus is anomocytic and exists in abaxial epidermis of all species, and in the adaxial epidermis of some species. Under SEM observation, the leaf epidermis was often striated, seldom nearly smooth, and often with flakes attached. Evidence from leaf epidermis serves as a criterion for distinguishing the subsections in sect. Meclatis (Spach) Tamura and in sect. Fruticella Tamura. The results also support that there are several separate evolutionary processes in the genus Clematis .
