Son La Prov., Van Ho Distr., Tan Xuan Municipality, Cot Moc village, territory of Xuan Nha natural reserve, eastern slopes of Pha Luong Mountain.
Remnants of primary and secondary broad-leaved evergreen humid forest on very steep mountain slopes composed by shale and sandstone at elevation about 900-1450 m a.s.l. around point 20°40′33.3″N 104°39′00.3″E.
Terrestrial and lithophytic herb 0.5-1 m tall on very steep, rocky humid and wet slope of small stream. Inflorescences white-gray. Very common to abundant.