N. Vietnam, Prov. Quang Binh, distr. Minh Hoa, 72 km to NWW from Dong Hoi, municipalite Thong Hoa, vicinities of Yen Son village, limestone massif Ke Bang (N 17°40′ E 105°57′). Primary evergreen open broadleaved dry forest on top of limestone mesas at 550-600 m alt. Woody vine up to 10 m lg. Flowers dull-yellowish. Not common. VH 4700 16.05.1997 International Botanical Expedition of the U.S.A. National Geographic Society (grant No 5803-96)