Northern Vietnam, Ha Tinh Prov., Huong Son Distr., Son Kim Municipality, in the vicinity of Rao An village, around point 18°22′00′'N, 105°13′13′'E. Primary evergreen lowland seasonal broad-leaved forest on granite along flat rocky river valley at 240-260 m a.s.l. Woody vine 20-30 m lg up to 10 cm in diam. Not rare.