FLORA OF VIETNAM Plants of Phong Nha - Ke Bang National Park Orchidaceae Dendrobium williamsonii Rchb.f.. ? (Sect. Nigrohirsutae). (Vel D. ochraceum De Wild., D. virgineum Rchb.f.).
Vietnam, Quang Binh Prov., Minh Hoa Distr., Thuong Hoa Municipality, about 2 km to E of Ban On village (17°40′21′'N, 105°58′00E).
Heavily logged primary and secondary closed evergreen broad-leaved forest and scrub on rocky ridge composed with solid and stratified marble-like highly eroded crystalline limestone at elevation 550-650 m a.s.l.
Epiphyte (on Pistacia cucphuongensis, Phyllanthus sp., Memecylon sp., Quercus sp.)along tops of ridge. Not common.