The genusEleutherococcus Maxim, is divided into five sections based on the morphology;Eleutherococcus, Cissifolius C.H. Kim and B.-Y. Sun (sect, nov.),Acanthopanax (Decne. & Planch.) H. Ohashi,Cephalopanax (Baill.) H. Ohashi andZanthoxylopanax (Harms) H. Ohashi. SectionAcanthopanax is further divided into two subsections;Acanthopanax andIonostachyae (Nakai) C.H. Kim & B.-Y Sun (comb. nov.). The new sectCissifolius is distinguished from others in having five fused carpels with free styles, solitary umbels at the end of branches, dioecious sexuality, and absence of tufted hairs in abaxial surface of leaf veins. The new section is most closely related toAcanthopanax in having free styles, solitary umbels, and dioecious sexuality. It is also related toEleutherococcus in having five carpels and lacking tufted hairs on abaxial surface of leaves. SectionCephalopanax shares all characteristics other than the number of carpels withEleutherococcus. SectionZanthoxylopanax is closely related toAcanthopanax in having two carpels with free styles, while it is also related toCephalopanax by having bisexual flowers and umbels arranged in a simple cyme. Considering the evolutionary trend in the family Araliaceae, five-carpellate sectionsEleutherococcus andCissifolius are more primitive than two-carpellate sectionsAcanthopanax, Cephalopanax, andZanthoxylopanax. SectionZanthoxylopanax seems to be intermediate betweenAcanthopanax andCephalopanax.