N. Vietnam, Prov. Thai Nguyen, distr. Dai Tu, vicinities of Tam Dao town, NE macroslope of Tam Dao ridge at 950-1000 m alt. (N 21°27′ E 105°38′). Closed wet evergreen broadleaved primary forest on very steep mt slope. Shrublet up to 0.4 m hg. Flowers white, often with light violet tint. Common. VH 4996 31.05.1997 International Botanical Expedition of the U.S.A. National Geographic Society (grant No 5803-96)