Reduction of Clematis dingjunshanica (Ranunculaceae) to the synonymy of C. hexapetala, with a review on the ambiguity of the name C. angustifolia

Based on our observations of herbarium specimens (including type material) and living plants in the wild, we demonstrate that Clematis dingjunshanica described from Mianxian county in Shaanxi province, China, is not essentially different from C. hexapetala in any morphological characters, a species that is particularly common in northern China and also occurs in Korea, Mongolia, and Russia (eastern Siberia). We therefore place C. dingjunshanica in synonymy with C. hexapetala herein. We also discuss the ambiguity of the name C. angustifolia, to which sometimes C. hexapetala was reduced as a synonym.