N.Vietnam, Bac Kan Prov., Cho Don Distr., Ban Thi Municipality, village Phia Khao, around point 22°15′52′'N, 105°32′01′'E at elevation 800-900 m a.s.l. (Po Luong mountain).
Primary broad-leaved evergreen closed forest on very steep slopes and
cliffs near and on tops of rocky ridge composed with solid marble-like stratified limestone.
Treelet 4-6 m tall. Flowers light violet. Not common.