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 650-900 m alt. Epiphytic shrublet with pendant shoots up to 1 m lg near and on tops of mesas. Flowers lemon-yellow, tepals usually with few crimson marks or pure yellow. Not rare, sometimes abundant. VH 4914 25-27.05.1997 International Botanical Expedition of the U.S.A. National Geographic Society (grant No 5803-96)