N. Vietnam, Prov. Cao Bang, distr. Tra Linh, municipalite Quoc Toan, vicinity of Thang Heng and Lung Tao villages near Thang Heng lake. Open dry primary mixed forest with domination of Keteleeria fortunei on tops of limestone mesas and ridges at 750-800 m alt. Terrestrial herb in open places on and near tops of mesas. Flowers from light violet to white, slightly greenish. Common. VH 4921 25-27.05.1997 International Botanical Expedition of the U.S.A. National Geographic Society (grant No 5803-96)