N.Vietnam, Thanh Hoa Prov., Ba Thuoc Distr., Co Lung Municipality, Khuyn village, around point 20°26′31′'N, 105°14′55′'E. Secondary evergreen seasonal broad-leaved forest on slope of river shale valley at foothill of crystalline marble-like highly eroded limestone ridge at elev. 50-70 m. Woody vine 10-20 m. Flowers bright red-orange. Common.