Foliar flavonoids of two sections of genus dendropanax in China, Japan, and Korea

Dendropanax, Araliaceae is a relatively small genus, which is composed of two sections, Dendropanax and Columnistylus. Foliar flavonoids were examined from 13 taxa of Dendropanax from China, Korea, and Japan. A total of 11 compounds were isolated and identified, mainly with the glycosides of the flavonols (kaempferol, and quercetin) and C-glycosylflavones (apigenin and luteolin). The majority of flavonoids fell into two major groups: a) flavonol and C-glycosylflavone (sect. Dendropanax) and b) flavonol only (some taxa of sect. Columnistylus). The analyzed flavonoid profiles were relatively simple, but showed that D. proteus and D. hainanensis of sect. Columnistylus were distinct from other taxa. On the other hand, tabulation of the identified flavonoid of the taxa within sect. Dendropanax failed to clearly distinguish among the species due to the similarity of their flavonoid profile. Dendropanax morbiferus and D. trifidus in Korea and Japan caused frequent difficulty in identification. The morphological differentiation between D. morbiferus and D. trifidus was not considered sufficient to warrant recognition of either specific or varietal status and they therefore should be treated as conspecific under D. trifidus. Additionally D. dentigerus in central and southern China was distinguished from D. trifidus only by leaf shape. The close morphological association indicated that even D. dentigerus was only weakly differentiated from D. trifidus. The taxonomic confusion surrounding D. trifidus and D. dentigerus will only be resolved and clarified using many reproductive individuals, rather than high variable vegetative characteristics.