N. Vietnam, Prov. Quang Binh, distr. Minh Hoa, 72 km to NWW from Dong Hoi, municipalite Thong Hoa, vicinities of Yen Son village, limestone massif Ke Bang (N 17°40′ E 105°57′). Broadleaved evergreen closed primary forest on steep slopes and bluffs of limestone mesas at 400-450 m alt. Epilitic herb up to 0.6 m hg on vertical shadow limestone bluffs. Flowers deep violet. Rare. VH 4770 17.05.1997 International Botanical Expedition of the U.S.A. National Geographic Society (grant No 5803-96)