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 of limestone mesas and ridges at 500-650 m alt. Epilite on shadow vertical limestone bluffs. Leaves green above, brightly deep red-purple below. Very common at 500-600 m alt. VH 4865 25-27.05.1997 International Botanical Expedition of the U.S.A. National Geographic Society (grant No 5803-96)