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 700-800 m a.s.l. Terrestrial herb among shady rocks along stream. Very common at elev. 700-1000 m a.s.l.