Vietnam, Lang Son Prov., Bac Son Distr., Tan Tri Municipality, around Na Mau village.
Highly degraded primary and secondary broad-leaved evergreen forest on very steep slopes and along tops of ridge composed with solid highly eroded crystalline gray marble-like limestone at elevation about 500-600 m a.s.l.
Lithophytic and terrestrial herb up to 1 m tall on open rocky tops of ridge. Flowers white. Very common.