N. Vietnam, Prov. Cao Bang, distr. Tra Linh, municipalite Quoc Toan, vicinity of Thang Heng and Lung Tao villages near Thang Heng lake. Broadleaved evergreen closed primary forest on steep slopes and bluffs on and near tops of limestone mesas and ridges at 800-900 m alt. Epilitic fern on open vertical bluffs near top of mesas. Not common. VH 4875 25-27.05.1997 International Botanical Expedition of the U.S.A. National Geographic Society (grant No 5803-96)