Northern Vietnam, Ninh Binh Prov., Nho Quan Distr., Cuc Phuong Municipality, Cuc Phuong National Park, about 1.5 km N from Bong locality, 20°21′01′'N, 105°35′38′'E. Remnants of primary closed evergreen seasonal broad-leaved lowland forest on rocky slopes of stream valley between limestone hills at elev. about 450 m a.s.l. Terrestrial herb up to 2 m tall. Flowers light dull yellowish. Locally very common.