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 broad-leaved primary forest on very steep mt slope. Epilitic herb on shadow vertical rocky bluffs. Flowers deep blue. Very common. VH 5013 31.05.1997 International Botanical Expedition of the U.S.A. National Geographic Society (grant No 5803-96)