N. Vietnam, Hoa Binh prov., Mai Chau distr., Hang Kia municipality, near Hang Kia village (20°43′39′'N, 104°53′43′'E). Primary broad-leaved evergreen wet forest on remnant limestone highly eroded ridge at elev. 1100-1300 m a.s.l. Herb vine 3-4 m on open rocks. Flowers violet. Occasionally common.