N. Vietnam, Hoa Binh prov., Da Bac distr., near Doan Ket village (20°54′58′'N, 105°03′51′'E). Primary broad-leaved evergreen wet forest on steep slopes of remnant highly eroded limestone ridge at elev. 750-900 m a.s.l., White Rock mt. (Nui Da Trang). Woody vine or climbing shrub on open slope. Young inflorescences green. Not common.