N. Vietnam, Thanh Hoa prov., Ba Thuoc distr., Co Lung municipality, territory of Pu Luong protected area, near Co Lung village, Nui Doan (Pha Doan) mountain system (20°26′30′'N, 105°11′32′'E). Primary evergreen broad-leaved dry forest along tops of remnant highly eroded karst limestone ridge at elev. 500-550 m a.s.l. Litophyte herb on crevices of vertical shady cliffs. Flowers white with yellow spot on center of median tepal. Occasionally very common.