N. Vietnam, prov. Cao Bang, distr. Nguyen Binh, municipality Ca Thanh, vicinities Ca Lu village, about 7-8 km to SE from Yen Lac village (N 22°44′ E 105°50′), about 38 km to NWW from Cao Bang town. Old open mixed semideciduous and coniferous (with Pseudotsuga brevifolia) primary forest along tops of limestone ridge and on steep slopes near ridge tops at 1350-1450 m alt. Woody vine up to 12 m lg. Flowers pale yellowish. Not rare.
CBL 553 21 Nov. 1998
International Botanical Expedition of the U.S.A. National Geographic Society (grant No 6300-98)