Northern Vietnam, Ninh Binh Prov., Nho Quan Distr., Cuc Phuong Municipality, Cuc Phuong National Park, Dang locality, about 1 km WNW of Dang forest Control point, 20°16′28′'N, 105°40′57′'. Secondary closed evergreen seasonal broad-leaved lowland forest on slopes of limestone hills at elev. 200-250 m a.s.l. Terrestrial herb up to 30 cm hg on open wet rocky slope. Flowers white, calyx light purple-violet. Common.