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. Closed secondary and remnants of primary broad-leaved evergreen forest on very steep rocky slopes of rocky ridges and mesae composed with light gray solid marble-like highly eroded crystalline limestone. Creeping lithophyte on very steep rocky slope. Common. HAL 5702 13 June 2004