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 sedge on open mossy rocks. Common, particularly on tops of ridge.