N. Vietnam, Hoa Binh prov., Da Bac distr., Cao Son municipality, Buoi Truong station near Ba Tri Mountain (20°52′31′'N, 105°11′48′'E). Secondary evergreen broad-leaved forest with bamboo on very steep shale slope with quartzite along river at 500-550 m a.s.l. Terrestrial herb 1.5 m hg on steep wet open slope. Flowers: lateral tepals light yellow-green with central purple stripe, lip light yellow with purple lateral stripe. Not common.