N. Vietnam, Hoa Binh prov., Da Bac distr., 4-6 km to the N of Doan Ket village, Phu Canh mountain system (20°55′48′'N, 105°02′52′'E). Primary wet broad-leaved evergreen closed mountain forest on sandstone and shale with quartzite at elev. 800-1000 m a.s.l. Woody vine 20-25 m lg in canopies of large trees. Young leaves pink-brown, flower buds light yellowish-green. Not common.