N. Vietnam, Thanh Hoa prov., Ba Thuoc distr., Co Lung municipality, territory of Pu Luong protected area, near Pu Luong village (20°27′01′'N, 105°11′03′'E). Secondary open forest and shrubs on steep alluvial clay slope at foothills of remnant highly eroded limestone ridge at elev. 100-150 a.s.l. Climbing shrub 2-3 m hg. Inflorescence greenish. Common.