N. Vietnam, Tuyen Quang prov., Na Hang distr., Xuan Tam municipality, near Ban Cai village (22°29′18′'N, 105°19′47′'E). Primary broad-leaved evergreen wet forest on alluvial foothills of highly eroded remnant limestone ridge at elev. 350-400 m a.s.l. Terrestrial herb on shady slope. Flower buds dirty yellowish. Not rare.