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. Epilite on steep shadow rocky slopes and vertical rocky bluffs. Very common. VH 5052 31.05.1997 International Botanical Expedition of the U.S.A. National Geographic Society (grant No 5803-96)