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 1000-1400 m a.s.l. around point 20°40′33.3″N 104°39′00.3″E.
Terrestrial erect herb 1.5-2 m tall on grassy steep slope. Flowers purple-violet. Locally common.