Floating-leaved aquatic, rooting in mud at bottom. Leaves shining ± olive-green above, purple-flushed beneath. Flowers opening well above water surface. Sepals pale blue inside. Petals 4-4.3 x 0.9-1.1 cm, ± elliptic, deep blue. Stamens 1.5-2 cm long, yellow filaments, purple-blue anthers. A few plants.