Son La Prov., Van Ho Distr., Chieng Xuan Municipality, Co Hong village, territory of Xuan Nha natural reserve, Pha Luong Mountain. Remnants of primary and secondary broad-leaved evergreen forest on very steep mountain slopes composed by brown sandstone at elevation 700-1000 m a.s.l. around point 20°42’14.2’’N 104°43’53.9’’E. Terrestrial and lithophytic herb on very steep rather open mossy slopes along narrow ridge edge. Common.