Nymphaeaceae

Aquatic perennial plants with large floating leaves and single large long-stalked flowers, both arising from a stout horizontal underground stem (rhizome); includes Water-lilies and Pond-lilies.

Sepals 4 to 6, green or reddish in Water-lilies, and yellow, petal-like, and showy in Pond-lilies. Petals numerous, conspicuous, showy and white or pink in Water-lilies and inconspicuous, yellowish and much smaller than sepals in Pond-lilies. Stamens numerous; in Water-lilies the outer ones with linear stalks (filaments) and the outer ones becoming progressively widened and petal-like. Carpels 5 to 35, united into an ovary that has multiple seed-chambers and is constricted beneath an expanded disk. Fruit a capsule or berry.

Floating leaves are large (10-30 cm wide), round to elliptic, and have a deep notch and pointed to rounded lobes. Submersed leaves none to broad and membranous, often disappearing by late season. The stalks of the leaves and flowers have minute to large air cavities. Leaf scars on massive spongy underground stems (rhizomes) may be circular, semicircular, winged or triangular.