N. Vietnam, Hoa Binh prov., Da Bac distr., Cao Son municipality, Nui Hen (Ba Tri) mountain system (20°54′09′'N, 105°12′15′'E). Remnants of primary forest among secondary wet broad-leaved evergreen forest with bamboo on very steep mountain slopes based on shale and sandstones with quartzite at 900-1100 m a.s.l. Terrestrial herb on very steep slope. Leaves deep green, sometimes with white spots above. Flowers black with dull yellowish-green center and tips of tepals. Locally abundant at elev. 1100-1150 m.