FLORA OF VIETNAM Orchidaceae Dendrobium williamsonii Rchb.f.
N. Viet Nam. Ha Giang Province, Quang Ba District, at Sin Suoi Ho village and river. Degraded agricultural land among limestone rocks to ridgetop of exposed limestone under light canopy with many epiphytes and lithophytes on north and east facing slopes, at 23°06′57″N, 105°01′48″E, at 514-900 m. Epiphyte on low tree at ridge. Sheaths with black hairs, flower buds light cream-green, petals lighter yellow, lip with orange at opening.