Phreatia densiflora (Blume) Lindl. var vietnamensis Aver.
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′). Primary evergreen open broadleaved dry forest on top of limestone mesas at 500-550 m alt. Epiphyte on tops of mesas. Not common. VH 4673 16.05.1997 International Botanical Expedition of the U.S.A. National Geographic Society (grant No 5803-96)