N. Vietnam, prov. Son La, distr. Moc Chau, municipality Chieng Hac, vicinities of Co Liu village (N 20°51′ E 104°38′). Remnants of primary evergreen broadleaved forests on vertical limestone bluffs along Xap river canyon at 550-600 m elev. Terrestrial forb up to 1 m hg among open rocks. Flowers white. Not rare.
NTH 2913 28 May 1999
International Botanical Expedition of the U.S.A. National Geographic Society (grant No 6300-98)