Northern Vietnam, Thanh Hoa Prov., Thach Thanh Distr., Thanh Yen Municipality, Mo village, around point 20°17′36′'N, 105°35′54′'. Remnants of prinary evergreen seasonal broad-leaved lowland dry forest on steep rocky slope of limestone hills at elev. about 300-350 m a.s.l. Herb or shrublet about 0.5 m tall on open cliff near the top of hill. Flowers white. Very common.