Son La Prov., Moc Chau Distr., Chieng Hac Municipality, around point 20°51′50″N 104°31′17″E.
Broad-leaved evergreen dry forest on steep slopes and on tops of ridge composed with rocky crystalline solid marble-like highly eroded limestone at elev. 1200-1300 m a.s.l.
Terrestrial herb up to 1.5 m tall on steep rather open slopes. Flowers blue-violet, honey fragrant. Locally common.
HAL 9417 31 Oct. 2006 Coll.: Nguyen Tien Hiep, L.Averyanov, Pham Van The.