N. Vietnam, prov. Cao Bang, distr. Ha Lang, municipality Thang Loi, vicinities of Lung Sam village (N 22°45′ E 106°42′). Secondary open semideciduous broadleaved forest along tops of remnant karst limestone ridge at 650-700 m elev. Woody vine 3-4 m lg on open rocks. Flowers dull yellowish. Very common.
CBL 1683 24 April 1999
International Botanical Expedition of the U.S.A. National Geographic Society (grant No 6300-98)