Houphan Prov., Viengxay Distr., Xieng Luong village, around point 20°22'06.1''N 104°17'18.6''E. Primary and secondary broad-leaved evergreen dry forest on very steep rocky slopes of highly eroded mountains composed by solid marble-like limestone at elev. 600-700 m a.s.l. Lithophytic undershrub on mossy shady rocks on mountain top. Common.