N.Vietnam, Bac Kan Prov., Cho Don Distr., Ban Thi Municipality, village Phia Khao, around point 22є17'31''N, 105є31'51''E, Cau Muc mountain at elevation 800-900 m a.s.l. Primary broad-leaved evergreen closed forest on very steep slopes and
cliffs near tops of rocky ridge composed with solid marble-like stratified limestone. Lithophytic herb or hemishrub up to 0.8 m tall on open rocks and cliffs. Flowers light violet. Common.