N.Vietnam, Bac Kan Prov., Na Ri Distr., Liem Thuy Municipality, village Na Bo, around point 21°56′44′'N, 106°05′09′'E, at elevation 300-700 m a.s.l.
Primary broad-leaved evergreen closed wet forest on very steep slopes and cliffs of rocky ridges and mesae composed with white solid marble-like crystalline limestone.
Herbaceous or hemiwoody vine on tops of ridge. Flower buds greenish. Occasional.