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 broad-leaved evergreen forest on very steep slopes of remnant highly eroded karst limestone ridge at elev. 600-700 m a.s.l. Terrestrial herb up to 1 m hg in wet places. Leaves uniform green above, deep uniform purple-violet below. Flower buds white. Occasional.