S. Vietnam, Prov. Ninh Thuan, distr. Ninh Son, municipalite Phuoc Binh, 37 km to NE from Dalat city. Closed primary broadleaved mt forest on E macroslope of Gia Rinh mt. ridge at 1400 m alt. (N 12° 06′, E 108° 43′). Woody vine with milky juice about 6-8 m lg. Flowers white. Not rare. VH 3545 02.04.1997 International Botanical Expedition of the U.S.A. National Geographic Society (grant No 5803-96)