N. Vietnam, Tuyen Quang prov., Na Hang distr., Thanh Tuong municipality, near Ban Bung village (22°16′26′'N, 105°25′58′'E). Primary broad-leaved evergreen wet forest on very steep limestone/shale slope of mountain stream canyon at elev. 300-450 m a.s.l. Terrestrial creeping herb in shady rocky slope. Young flowers greenish dirty-brown, old - brownish-black, white haired along margin, tepals outside light dirty-green. Locally abundant.