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 and lithophyte forb on steep open wet slopes. Flowers light blue. Very common.
NTH 2925 28 May 1999
International Botanical Expedition of the U.S.A. National Geographic Society (grant No 6300-98)