N. Vietnam, prov. Cao Bang, distr. Thach An, municipality Duc Xuan, (N 22°21′ E 106°27′), about 39 km to SSE from Cao Bang town. Primary broadleaved semideciduous forest on steep slopes near tops of remnant limestone ridge at 500 m alt. Shrublet or herb up to 2 m hg on open rocks. Flowers deep blue-violet. Not rare.
CBL 814 02 Dec. 1998
International Botanical Expedition of the U.S.A. National Geographic Society (grant No 6300-98)