Vietnam, Quang Binh Prov., Bo Trach Distr., Tan Trach Municipality, about 1.5 km to SE of A Rem village (17º23'32''N, 106º12'46''E). Primary closed coniferous forest (with Calocedrus rupestris) on steep slopes and on tops of rocky ridge composed with solid marble-like highly eroded stratified crystalline limestone at elevation about 750-900 m a.s.l. Lithophytic herb on vertical mossy cliffs. Flowers light blue. Common.