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 m a.s.l.
Herb or hemishrub 0.5 m tall on shady stream bluffs. Flower buds light greenish. Not common.