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.
Woody grass with stems to 15 m tall and 25 cm in diam. in alluvial valley between limestone mountains among open secondary scrub in wet place along small stream. Stamens dull yellow, flowers visited by many bees. Common.