FLORA OF VIETNAM
Orchidaceae
Dendrobium williamsonii Day & Rchb.f.

Ha Giang prov., Quan Ba distr., Tung Vai commune, Thang village, around point 23°03ʹ04.2ʺN 104°51ʹ09.7ʺE, steep rocky slopes near mountain top composed with eroded stratified highly eroded limestone at elevation 1200-1450 m a.s.l. Primary evergreen broad-leaved very humid forest. Epiphyte on tall mossy tree. Flowers yellowish, lip with orange center. Not rare. 24 April 2018, L. Averyanov, Nguyen Sinh Khang, Nguyen Tien Hiep, Nguyen Quang Hieu, Chuong Quang Ngan, T. Maisak, VR 781 (HN, LE01048850, LE01054209).