N.Vietnam, Cao Bang Prov., Trung Khanh Distr., Ngoc Khe Municipality, Pac Nga village, around point 22є54'59''N, 106є31'44''E, at elevation 700-800 m a.s.l. Remnants of primary broad-leaved evergreen and coniferous forest along tops of rocky ridges and mesae composed with light gray solid marble-like highly eroded crystalline limestone. Treelet 4-6 m tall. Flowers light yellow, fruits green. Very common. Co-dominant of 3 forest stratum.