N.Vietnam, Thanh Hoa Prov., Ba Thuoc Distr., Co Lung Municipality, Khuyn village, around point 20°26′31′'N, 105°14′55′'E. Primary evergreen seasonal broad-leaved lowland forest on crystalline marble-like highly eroded limestone, N slopes of limestone ridge at elev. 260-320 m. Terrestrial herb. Flowers white. Leaves deep green above, brown-purple below. Occasional.