Abstract:Species delimitation of the Chinese endemic genus Clematoclethra (Actinidiaceae) has been greatly controversial due to overlapping variations of morphological features and distribution. It was classified into 20 species or treated as a monotypic genus containing 1 species with 4 subspecies. In this study, leaf epidermal morphology of 184 specimens from 29 populations covering its distribution were investigated using light microscope and scanning electron microscope (SEM) in order to provide some clues to its taxonomy. The results indicated that: (1) the leaf trichomes morphology of genus Clematoclethra varied greatly which were grouped into three types (the glabrous type with few short pillar hairs, the setose type with long pillar/stab hairs, the woolly type with the uniserate hairs). And due to the obvious variation of leaf trichomes among the populations, members of Clematoclethra should be classified into three groups (the glabrous group, the setose group, and the wooly group) with a disjunctive geographically distribution. (2) Additionally, the three groups of Clematoclethra also appeared to be distributed partially with a sympatric pattern in several populations and with a vertical geographically one in 3 populations at different altitudes in Emei Mountain. (3) The other characters of leaf epidermis of Clematoclethra, such as the irregular epidermal cells, 6 types of stomata, reticulum waxy sculptures with 2-4 types of secondary waxy sculptures, commonly and randomly observed in all populations, might have no taxonomic significance. (4) Based on the shared features of leaf epidermis and overlapping distribution, it was suggested that C. scandens subsp. hemsleyi might be grouped into C. scandens subsp. tomentella. Therefore, it was supported that Clematoclethra should be treated as a monotypic genus of ongoing speciation, containing 1 species with 3 subspecies.