N.Vietnam, Ha Tinh Prov., Huong Son Distr., Son Kim Municipality, Rao Bun stream around point 18°23′39′'N, 105°15′12′'E. Primary broad-leaved evergreen closed wet forest on very steep shale slopes of
river canyon at elevation about 300-400 m a.s.l.
Creeping epiphytic vine 15-20 m long. Flowers white to yellow, spathe olive-violet. Very common.