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 slopes of remnant limestone highly eroded ridge at elev. 1100 m a.s.l. Treelet 6-8 m hg on steep open slope. Flowers light green. Rare.