Nelumbo is a genus of aquatic plants with large, showy flowers. Members are commonly called lotus, though "lotus" is a name also applied to various other plants and plant groups, including the unrelated genus Lotus. Members outwardly resemble those in the family Nymphaeaceae ("water lilies"), but Nelumbo is actually very distant to Nymphaeaceae. "Nelumbo" is derived from the Sinhalese word Sinhalese: ?????? ne?um, the name for the lotus Nelumbo nucifera.
There are only two known living species of lotus; Nelumbo nucifera is native to Asia and is better-known. It is commonly cultivated; it is eaten and used in traditional Chinese medicine. This species is the floral emblem of both India and Vietnam.
The other lotus is Nelumbo lutea and is native to North America and the Caribbean. Horticultural hybrids have been produced between these two allopatric species.
There are several fossil species known from Cretaceous, Paleogene and Neogene aged strata throughout Eurasia and North America.
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Species
Extant species
- Nelumbo lutea Willd. - American lotus (Eastern United States, Mexico, Greater Antilles, Honduras)
- Nelumbo nucifera Gaertn. - sacred or Indian lotus, also known as the Rose of India and the sacred water lily of Hinduism and Buddhism. It is the national flower of India and Vietnam. Its roots and seeds are also used widely in Asian cooking.
Fossil species
- +Nelumbo aureavallis Hickey - Eocene (North Dakota), described from leaves found in the Golden Valley Formation in North Dakota, USA.
- +Nelumbo changchangensis Eocene, (Hainan Island, China), described from several fossils of leaves, seedpods, and rhizomes from the Eocene-aged strata in the Changchang Basin, of Hainan Island.
- +Nelumbo minima Pliocene (Netherlands), described from leaves and seedpods that suggest a very small plant. Originally described as a member of the genus Nelumbites, as "Nelumbites minimus."
- +Nelumbo nipponica Eocene-Miocene, fossil leaves are known from Eocene-aged strata in Japan, and Miocene-aged strata in Russia.
- +Nelumbo orientalis Cretaceous (Japan), one of the oldest known species, fossils are found in Cretaceous-aged strata of Japan.
- +Nelumbo protolutea Eocene (Mississippi), fossils of leaves strongly suggest a plant similar in form to the American lotus.
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Classification
There is residual disagreement over which family the genus should be placed in. Traditional classification systems recognized Nelumbo as part of the Nymphaeaceae, but traditional taxonomists were likely misled by convergent evolution associated with an evolutionary shift from a terrestrial to an aquatic lifestyle. In the older classification systems it was recognized under the biological order Nymphaeales or Nelumbonales. Nelumbo is currently recognized as a only living genus in Nelumbonaceae, one of several distinctive families in the eudicot order of the Proteales. Its closest living relatives, the (Proteaceae and Platanaceae), are shrubs or trees.
The leaves of Nelumbo can be distinguished from those of genera in the Nymphaeaceae as they are peltate, that is they have fully circular leaves. Nymphaea, on the other hand, has a single characteristic notch from the edge in to the center of the lily pad. The seedpod of Nelumbo is very distinctive.
APG
The APG IV system of 2016, recognizes Nelumbonaceae as a distinct family and places it in the order Proteales in the eudicot clade, as do the earlier APG III and APG II systems.
Earlier classification systems
The Cronquist system of 1981 recognizes the family but places it in the water lily order Nymphaeales. The Dahlgren system of 1985 and Thorne system of 1992 both recognize the family and place it in its own order, Nelumbonales.
Characteristics
Superhydrophobicity
The leaves of nelumbo are highly water-repellent (i.e. they exhibit ultrahydrophobicity) and have given the name to what is called the lotus effect.
Thermoregulation
Nelumbo nucifera regulates its temperature in order to benefit insect pollinators. When the plant flowers, it heats its blossoms to above 30 °C (86 °F) for as long as four days even when the air is as cool as 10 °C (50 °F). The heat releases an aroma that attracts certain insects, which fly into the flower to feed on nectar and pollen. According to Roger Seymour and Paul Schultze-Motel of Australia's University of Adelaide, the heat also rewards insects with a stable environment that enhances their ability to eat, mate, and prepare for flight.
Cultural significance
The sacred lotus, N. nucifera, is sacred in both Hinduism and Buddhism.
Source of the article : Wikipedia
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