Floating leaves up to 10 Χ 5 cm, ovate to lanceolate, cuneate to subcordate at the base, translucent; petiole not longer than the lamina. Submerged leaves up to 18 cm, petiolate, similar to the floating leaves but narrower, obtuse, entire. Stipules membranous, with well-separated, slender veins. Fruitlets 1·5-1·75 mm, greenish. 2n = 26. Usually in calcareous waters. W. & C. Europe, extending to S. Sweden.