Water Lily, common name for a small family of aquatic flowering plants, and for its representative genus. The family includes about 70 species.

Its leaves are usually peltate, that is, the leafstalk (petiole) is attached at the center of the leaf rather than at an edge. The leaves often float on the water's surface, maintaining their position, even if the water rises, by continuing stalk growth. Water lilies typically grow in quiet waters covering deep, saturated, oxygen-poor soils. Oxygen needed for root growth is supplied by air passages extending down the leaf petioles. Many water lilies are grown as pond ornamentals, and numerous hybrids have been produced.

Members of the representative genus, with floating leaves, are also called lotus. Two species were both represented in ancient Egyptian art. The family also contains the gigantic lilies of the Amazon.

The family is placed with three or four other families in an order that is cosmopolitan in distribution but restricted to freshwater habitats. In addition to being of aquatic habit, members of the order are characteristically herbaceous (nonwoody) and bear solitary rather than clustered flowers. The flower parts are usually numerous and unfused, traits found in orders that resemble the most ancestral flowering plants.

The lotus-lily family contains one genus, with two species: the sacred lotus, which is sacred to Buddhists, and the American lotus. The seeds and rhizomes of these lotuses are edible; the leaves are held above water on long stalks. The two species constituting the hornwort family are often grown in household aquariums. They grow totally submerged, usually even producing their flowers and fruits under water. They completely lack roots. The individual leaves are finely divided into narrow segments and grow in whorls at each node, giving the plants a raccoon-tail look. The water-shield family contains two genera and eight species of herbs; some are also used as aquarium plants.

Scientific classification: Water lilies make up the family Nymphaeaceae of the order Nymphaeales. The representative genus of the family is Nymphaea. The species represented in ancient Egyptian art are classified as Nymphaea caerula and Nymphaea lotus. The gigantic lilies of the Amazon are classified in the genus Victoria. The sacred lotus, classified as Nelumbo nucifera, and the American lotus, classified as Nelumbo lutea, belong to the family Nelumbonaceae.