N. Vietnam, Prov. Cao Bang, distr. Tra Linh, municipalite Quoc Toan, vicinity of Thang Heng and Lung Tao villages near Thang Heng lake. Dry broadleaved evergreen closed primary forest on steep slopes and bluffs of limestone ridges and mesas at 650-750 m alt. Epilitic rosette herb on shadow limestone bluffs. Leaves often with whitish tesselation. Flowers blue-violet. Not rare. VH 4903 25-27.05.1997 International Botanical Expedition of the U.S.A. National Geographic Society (grant No 5803-96)