N. Vietnam, Hoa Binh prov., Da Bac distr., about 2-3 km to the E of Doan Ket village (20°54′55′'N, 105°02′18′'E). Secondary open evergreen broad-leaved forest on very steep clay slopes at 600-700 m a.s.l. Herb vine 3-4 m lg in open second shrubs. Flowers light yellowish-green. Very common.