FLORA OF VIETNAM Rubiaceae Ophiorrhiza cantoniensis Hance
N.Vietnam, Thanh Hoa Prov., Ba Thuoc Distr., Co Lung Municipality, Eo Dieu village, around point 20°26′06′'N, 105°13′51′'E. Primary
evergreen seasonal broad-leaved closed submontane forest on top of rocky ridge composed with crystalline marble-like highly eroded limestone at elev. 900-1000 m. Terrestrial and lithophytic herb. Flowers light pink-violet. Leaves dull purple-violet below. Very common.