Clematis sinii and C. xinhuiensis (Ranunculaceae), respectively described from Guangxi and Guangdong of China, are merged with C. meyeniana, a species widely distributed in eastern and southeastern Asia

Based on literature consultation, specimen survey, and observations of living plants in the wild, we demonstrate that Clematis sinii and C. xinhuiensis (Ranunculaceae), respectively described from Guangxi and Guangdong of China, are not essentially different from C. meyeniana in any characters, a species widely distributed in eastern and southeastern Asia and morphologically highly variable. We therefore place both C. sinii and C. xinhuiensis in synonymy with C. meyeniana herein. Pollen morphology is not useful for distinguishing between C. meyeniana and its closely similar species. We also point out that further work is needed to thoroughly clear up much of the taxonomic confusion involving C. meyeniana and its morphologically similar taxa.