N. Vietnam, Hoa Binh prov., Da Bac distr., Cao Son municipality, Buoi Truong station near Ba Tri Mountain (20°52′31′'N, 105°11′48′'E). Secondary evergreen broad-leaved forest with bamboo on very steep shale slope with quartzite along river at 500-550 m a.s.l. Herb vine 5-7 m lg in open second shrubs on steep slope. Common.