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, or waterlilies in the United Kingdom. The genus name is from the Greek νυμφαία, nymphaia and the Latin nymphaea, which mean "water lily" and were inspired by the nymphs of Greek and Latin mythology. Description Water lilies are aquatic rhizomatous herbaceous perennials, sometimes with stolons as well. The stem is angular and erect. The leaves grow from the rhizome on long petioles (stalk that attaches the leaf blade to the stem). Floating round leaves of waterlily grow up to across. The disc-shaped leaf blades are notched and split to the stem in a at the centre, and are often purple underneath. Most of them float on the surface of the water. The leaves have smooth or spine-toothed edges, and they can be rounded or pointed. The flowers rise out of the water or float on the surface, opening during the day or at night. Many species of Nymphaea display protogynous flowering. The temporal separation of these female and male phases is physically reinforced by flower opening and closing, so the first flower opening displays female pistil and then closes at the end of the female phase, and reopens with male stamens. Each has at least eight petals in shades of white, pink, blue, or yellow. Many stamens are at the center. Water lily flowers are entomophilous, meaning they are pollinated by insects, often beetles. The fruit is berry-like and borne on a curving or coiling peduncle. The plant reproduces by root tubers and seeds. Taxonomy This is one of several genera of plants known commonly as lotuses. It is not related to the legume genus Lotus or the East Asian and South Asian lotuses of genus Nelumbo. It is closely related to Nuphar lotuses, however. In Nymphaea, the petals are much larger than the sepals, whereas in Nuphar, the petals are much smaller. The process of fruit maturation also differs, with Nymphaea fruit sinking below the water level immediately after the flower closes, and Nuphar fruit remaining above the surface. Subgenera Anecphya Brachyceras Hydrocallis Lotos Nymphaea: section Chamaenymphaea section Nymphaea section