Nymphaea is a genus of aquatic plants in the family Nymphaeaceae. There are about 50 species in the genus, which has a cosmopolitan distribution.
The common name, shared with some other genera in the same family, is Water Lily.
The name Nymphaea comes from the Greek term "Νυμφαία", possibly related to "Νύμφη" meaning "nymph". The nymphs in Greek mythology were supernatural feminine beings associated with springs, so the application of the name to delicately flowered aquatic plants is understandable.
Despite their name, water-lilies are not related to the true lilies (family Liliaceae). The name "lily" is applied to a number of plants that are not at all closely related, such as day lilies, spider lilies and arum lilies, in addition to the water lilies. Nymphaea (Egyptian lotuses) are also not related to the Chinese and Indian lotus of genus Nelumbo, which are used in Asian cooking and sacred to Hinduism and Buddhism.
However, the genus Nymphaea is closely related to Nuphar, another genus commonly called "lotus". In Nymphaea, the flower petals are much larger than the sepals, whereas in Nuphar the petals are much smaller than its sepals. The fruit maturation also differs, with Nymphaea fruit sinking below the water level immediately after the flower closes, whereas Nuphar fruit are held above water level to maturity. Both genera share leaves with a radial notch from the circumference to the petiole (leaf stem) in the center.
A water lily is also known as a lotus. Depictions of the lotus can be traced back to the tombs of ancient Egypt. The water lily is an important symbol in many religions including Buddhism and Hinduism.
There are more than 70 species of plants in the Nympheaceae family, including the water lily. The three types of water lily are the night, tropical and hardy.