N. Vietnam, Prov. Cao Bang, distr. Tra Linh, municipalite Quoc Toan, vicinity of Thang Heng and Lung Tao villages near Thang Heng lake. Remnant closed evergreen primary broadleaved forest in alluvial valley bottom between limestone ridges and mesas near karst lake at 500 m alt. Woody vine about 15 m lg in wet place near lake side. Not common. VH 4849 25-27.05.1997 International Botanical Expedition of the U.S.A. National Geographic Society (grant No 5803-96)