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 700-800 m a.s.l.
Open grassy place along border of agricultural field and closed secondary broad-leaved evergreen forest on lower part of very steep rocky slopes of rocky ridges and mesae composed with light gray solid marble-like highly eroded crystalline limestone.