Vietnam, Ha Giang Prov., Hoang Su Phi Distr., Ho Thau Municipality, around Trung Thanh village (22°37′24″N, 104°38′00″E) at elev. 900-1000 m a.s.l.
Remnants of heavily logged primary and secondary closed evergreen broad-leaved forest on very steep slopes of mountains composed with shale and granite with quartzite. Terrestrial herb up to 1.5 m tall on very steep shady rocky slope of narrow river canyon. Leaves uniform green, flowers white. Occasional.