Phylogeny of Celastrus L. (Celastraceae) inferred from two nuclear and three plastid markers.

This is the first comprehensive molecular investigation of the genus Celastrus L. Phylogenetic relationships within the genus were assessed based on sequences of two nuclear (ETS, ITS) and three plastid (psbA-trnH, rpl16 and trnL-F) regions using the Bayesian inference and the maximum parsimony methods. Our results show that Celastrus, together with Tripterygium, formed a maximal supported clade. Within the cluster, Celastrus is composed of a basal clade and a core Celastrus clade, and the latter is consisted of six subclades. Relationships among species are more influenced by latitude than continental distribution patterns. The cauline cyme and lunate seeds are distinct characters to one of the maximal supported subclades. Their close relationship, similar geographical pattern and habitat imply that C. flagellaris may be a potential invasive species threatening C. scandens in North America. Celastrus leiocarpus, C. oblanceifolius and C. rugosus are confirmed as synonyms of C. punctatus, C. aculeatus and C. glaucophyllus, respectively. Discordance between the molecular data and previous morphology-based subgeneric classifications are noted. More works are needed to clarify the relationship between Celastrus and Tripterygium and the species within Celastrus.