N. Vietnam, prov. Cao Bang, distr. Ha Lang, municipality Thang Loi, vicinities of Lung Sam village (N 22°45′ E 106°42′). Secondary wet evergreen broadleaved forest with remnants of primary elements on steep slopes and bluffs of karst remnant limestone ridge at 500-550 m elev. Prostrate herb on mossy wet open rocks. Flowers white, sometimes with light lilac tint. Common. Commonest weed in the area.
CBL 1640 23 April 1999
International Botanical Expedition of the U.S.A. National Geographic Society (grant No 6300-98)