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 alluvial valley between limestone hills at elev. about 300 m a.s.l. Terrestrial and lithophytic herb up to 1.5 m tall. Flowers white, median tepal with red median longitudinal stripe and yellow apical part of keels. Common.