N.Vietnam, Ha Tinh Prov., Huong Son Distr., Son Kim Municipality, Rao Bun stream around Rao An FPD station at 18°25′18′'N, 105°13′15′'E. Primary and secondary broad-leaved evergreen closed wet forest on very steep shale slopes of river canyon at elevation about 200-300 m a.s.l. Terrestrial herb up to 1.5 m tall. Flowers white with yellowish-pink tint. Common.