N.Vietnam, Cao Bang Prov., Trung Khanh Distr., Ngoc Khe Municipality, Pac Nga village, around point 22º54'59''N, 106º31'44''E, at elevation 800-850 m a.s.l. Remnants of primary broad-leaved and coniferous forest on ridge tops and on very steep slopes and cliffs of rocky ridges and mesae composed with light gray solid marble-like highly eroded crystalline limestone. Lithophyte and epiphyte. Flowers white, light yellowish, lip light yellowish with olive-green keels and orange epichile. Common.