N. Vietnam, Thanh Hoa prov., Ba Thuoc distr., Eo Dieu municipality, territory of Pu Luong protected area, near Eo Dieu village (20°25′48′'N, 105°14′13′'E). Primary wet coniferous forest with Pinus kwangtungensis along tops of remnant highly eroded karst limestone ridge at elev. 900-1000 m a.s.l. Terrestrial and lithophytic herb on very steep rocky slope. Flowers white. Common, locally abundant.