N.Vietnam, Ha Tinh Prov., Huong Son Distr., Son Hong Municipality, around point 18°34′06′'N, 105°11′40′'E. Primary broad-leaved dry closed evergreen forest on very steep mt slopes of Khe Sinh stream canyon and along ridge composed with shale at elev. 800-1100 m a.s.l. near Laotian border.
Creeping epiphytic vine 6-8 m long. Flowers white. Occasional.