N. Vietnam, Thanh Hoa prov., Ba Thuoc distr., Co Lung municipality, territory of Pu Luong protected area, near Co Lung village (20°27′28′'N, 105°12′18′'E). Primary broad-leaved evergreen forest on slope of remnant highly eroded karst limestone ridge at elev. 500 m a.s.l. Terrestrial herb about 0.5 m hg on very steep slope. Not common.