Houphan Prov., Viengxay Distr., Vieng Xai village, around point 20°23'41.3''N 104°13'44.5''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. 800-950 m a.s.l. Epiphyte on old mossy tree. Locally common, particularly on mountain tops.