N. Vietnam, prov. Cao Bang, distr. Thach An, about 25 km to SSE from Cao Bang town (N 22°27′ E 106°22). Primary evergreen closed semideciduous forest on tops of remnant limestone ridge at 500 m alt. Terrestrial and epilite herb up to 1.5 m hg in open rocks. Not rare.
CBL 931 05 Dec. 1998
International Botanical Expedition of the U.S.A. National Geographic Society (grant No 6300-98)