N. lutea: leaves oblong-cordate; flowers yellow, raised two or three inches above the water, faintly scented, the concave sepals assuming a somewhat globular form; petals and stamens very numerous, scarcely more than half the length of the sepals. - Rivers and pools. Fl. July.
Var. pumila: plant smaller, flowers with a more indented stigmatic disk. - Lakes of the north of Scotland.