Northern Vietnam, Ha Tinh Prov., Huong Son Distr., Son Kim Municipality, in the vicinity of Rao An village, around point 18°22′00′'N, 105°13′13′'E. Primary evergreen lowland seasonal broad-leaved forest on granite rocky shady slopes of river valley at 260-360 m a.s.l. Terrestrial herb on shady steep rocky slope. Tepals green, anthers yellow. Not common.