Nymphaea is a genus of hardy and tender aquatic plants in the family Nymphaeaceae. The genus has a cosmopolitan distribution. Many species are cultivated as ornamental plants, and many cultivars have been bred. Some taxa occur as introduced species where they are not native, and some are weeds. Plants of the genus are known commonly as water-lilies. The genus name is from the Greek νυμφαια, nymphaia and the Latin nymphaea, which mean "water-lily" and were inspired by the nymphs of Greek and Latin mythology.