N. Vietnam, Prov. Cao Bang, Distr. Tra Linh, Subdistr. Quoc Toan, wet shadow evergreen forest on N clopes of remnant limestone mountains at 650-750 m alt. near Thang Heng lake in environs of Thang Hen and Kung Tao villages. Terrestrial herb to 1.5 m high. Flowers white, then yellowish, the lip light violet. Not common.