N. Vietnam, Son La prov., Moc Chau distr., Long Luong municipality, near Sang Cai village (20°45′51′'N, 104°51′26′'E). Primary wet broad-leaved evergreen and semideciduous mossy forest along remnant limestone highly eroded ridge at elev. 1300-1450 m a.s.l. Epiphytic woody vine 5-6 m lg. Not common.