N.Vietnam, Cao Bang Prov., Trung Khanh Distr., Ngoc Khe Municipality, Pac Nga village, around point 22°54′59′'N, 106°31′44′'E, at elevation 600-650 m a.s.l.
Closed secondary broad-leaved evergreen wet forest on very steep rocky slopes of rocky ridges and mesae composed with light gray solid marble-like highly eroded crystalline limestone.
Lithophytic herb up to 1.5 m tall. Flowers white, anthers yellow. Occasional.