N.Vietnam, Thanh Hoa Prov., Quan Hoa Distr., Phu Le Municipality, Hang village, around point 20°31′13′'N, 105°05′45′'E. Primary evergreen seasonal broad-leaved closed lowland forest on very steep slopes and cliffs of rocky ridge composed with crystalline marble-like highly eroded limestone at elev. 450-650 m. Terrestrial herb. Flowers purple-violet. Occasional.