N. Vietnam, prov. Lai Chau, about 50 km downstream along Black river (Song Da), from Lai Chau town (N 22°03′ E 103°09′) to Nam Ma village (distr. Sin Ho). Open shale and limestone rocks on steep slopes of the river at elev. about 220 m. Forb up to 0.6 m hg in open wet sandy places. Flowers purple-violet. Rare.
NTH 2740 24 May 1999
International Botanical Expedition of the U.S.A. National Geographic Society (grant No 6300-98)