Watermelon

Watermelon(Citrullus lanatus) is aflowering plantspecies of theCucurbitaceaefamily and the name of itsedible fruit. Ascrambling and trailingvine-like plant, it is ahighly cultivatedfruit worldwide, with more than 1,000varieties.
Watermelon is grown in favorableclimatesfromtropicaltotemperateregions worldwide for its large ediblefruit, which is aberrywith a hard rind and no internal divisions, and isbotanicallycalled apepo. The sweet, juicy flesh is usually deep red to pink, with many black seeds, althoughseedlessvarieties exist. The fruit can be eaten raw orpickled, and the rind is edible after cooking. It may also be consumed as a juice or an ingredient in mixed beverages.
Kordofanmelons fromSudanare the closest relatives and may beprogenitorsof modern, cultivated watermelons.Wild watermelon seeds were found inUan Muhuggiag, a prehistoric site inLibyathat dates to approximately 3500 BC.In 2022, a study was released that traced 6,000-year-old watermelon seeds found in the Libyan desert to the Egusi seeds ofNigeria, West Africa.Watermelons were domesticated in north-eastAfricaand cultivated inEgyptby 2000 BC, although they were not the sweet modern variety. Sweet dessert watermelons spread across the Mediterranean world duringRoman times.
Considerablebreedingeffort has developed disease-resistant varieties. Manycultivarsare available that produce mature fruit within 100 days of planting. In 2017,Chinaproduced about two-thirds of the world's total of watermelons.
The watermelon is anannualthat has a prostrate or climbing habit. Stems are up to 3 metres (10 feet) long and new growth has yellow or brown hairs. Leaves are60 to 200 millimetres (2+1⁄4to7+3⁄4inches) long and40 to 150 mm (1+1⁄2to 6 in) wide. These usually have three lobes that are lobed or doubly lobed. Young growth is densely woolly with yellowish-brown hairs which disappear as the plant ages. Like all but one species in the genusCitrullus, watermelon has branchingtendrils. Plants have unisexual male or female flowers that are white or yellow and borne on40-millimetre-long (1+1⁄2in) hairy stalks. Each flower grows singly in the leaf axils, and the species'sexual system, with male and female flowers produced on each plant, ismonoecious. The male flowers predominate at the beginning of the season; the female flowers, which develop later, have inferior ovaries. Thestylesare united into a single column.
The large fruit is a kind of modified berry called apepowith a thickrind(exocarp) and fleshy center (mesocarpand endocarp).Wild plants have fruits up to 20 cm (8 in) in diameter, while cultivated varieties may exceed 60 cm (24 in). The rind of the fruit is mid- to dark green and usually mottled or striped, and the flesh, containing numerouspipsspread throughout the inside, can be red or pink (most commonly), orange, yellow, green or white.
A bitter watermelon,C. amarus, has becomenaturalizedin semiarid regions of several continents, and is designated as a "pest plant" in parts ofWestern Australiawhere they are called "pig melon".
The sweet watermelon was first described byCarl Linnaeusin 1753 and given the nameCucurbita citrullus. It was reassigned to the genusCitrullusin 1836, under thereplacement nameCitrullus vulgaris, by the German botanistHeinrich Adolf Schrader.(TheInternational Code of Nomenclature for algae, fungi, and plantsdoes not allow names like "Citrullus citrullus".)
The species is further divided into several varieties, of which bitter wooly melon (Citrullus lanatus(Thunb.) Matsum. & Nakai var.lanatus),citron melons(Citrullus lanatusvar.citroides(L. H. Bailey) Mansf.), and the edible var.vulgarismay be the most important. This taxonomy originated with the erroneous synonymization of the wooly melonCitrullus lanatuswith the sweet watermelonCitrullus vulgarisbyL.H. Baileyin 1930.Molecular data, including sequences from the original collection of Thunberg and other relevant type material, show that the sweet watermelon (Citrullus vulgarisSchrad.) and the bitter wooly melonCitrullus lanatus(Thunb.) Matsum. & Nakai are not closely related to each other.A proposal to conserve the name,Citrullus lanatus(Thunb.) Matsum. & Nakai, was accepted by thenomenclaturecommittee and confirmed at theInternational Botanical Congressin 2017.
Prior to 2015, the wild species closest toCitrullus lanatuswas assumed to be the tendril-less melonCitrullus ecirrhosusCogn. from South African arid regions based on an erroneously identified 18th-century specimen. However, after phylogenetic analysis, the closest relative toCitrullus lanatusis now thought to beCitrullus mucosospermus(Fursa) from West Africa (from Senegal to Nigeria), which is also sometimes considered a subspecies withinC. lanatus.Watermelon populations from Sudan are also close to domesticated watermelons.The bitter wooly melon was formally described byCarl Peter Thunbergin 1794 and given the nameMomordica lanata.It was reassigned to the genusCitrullusin 1916 by Japanese botanistsJinzō MatsumuraandTakenoshin Nakai.
Watermelons were originally cultivated for their high water content and stored to be eaten during dry seasons, as a source of both food and water.Watermelon seeds were found in theDead Searegion at the ancient settlements ofBab edh-DhraandTel Arad.
Many 5000-year-old wild watermelon seeds (C. lanatus) were discovered atUan Muhuggiag, a prehistoric archaeological site located in southwesternLibya. This archaeobotanical discovery may support the possibility that the plant was more widely distributed in the past.
In the7th century, watermelons were being cultivated in India, and by the 10th century had reached China. TheMoorsintroduced the fruit into theIberian Peninsula, and there is evidence of it being cultivated inCórdobain 961 and also inSevillein 1158. It spread northwards throughsouthern Europe, perhaps limited in its advance by summer temperatures being insufficient for good yields. The fruit had begun appearing in Europeanherbalsby 1600, and was widely planted in Europe in the 17th century as a minor garden crop.
Early watermelons were not sweet, but bitter, with yellowish-white flesh. They were also difficult to open. The modern watermelon, which tastes sweeter and is easier to open, was developed over time throughselective breeding.
European colonists introduced the watermelon to theNew World.Spanish settlerswere growing it in Florida in 1576. It was being grown in Massachusetts by 1629, and by 1650 was being cultivated inPeru,BrazilandPanama. Around the same time,Native Americanswere cultivating the crop in the Mississippi valley andFlorida. Watermelons were rapidly accepted inHawaiiand otherPacific islandswhen they were introduced there by explorers such asCaptain James Cook.In theCivil War eraUnited States, watermelons were commonly grown by freeblack peopleand became one symbol for the abolition of slavery.After the Civil War, black people were maligned for their association with watermelon. The sentiment evolved into a raciststereotypewhere black people shared a supposed voracious appetite for watermelon, a fruit long associated with laziness and uncleanliness.
Seedless watermelons were initially developed in 1939 by Japanese scientists who were able to create seedlesstriploidhybridswhich remained rare initially because they did not have sufficientdisease resistance.Seedless watermelons became more popular in the 21st century, rising to nearly 85% of total watermelon sales in the United States in 2014.
A melon from theKordofanregion ofSudan– thekordofan melon– may be theprogenitorof the modern, domesticated watermelon.The kordofan melon shares with the domestic watermelon loss of the bitterness gene while maintaining a sweet taste, unlike other wild African varieties from other regions, indicating a common origin, possibly cultivated in the Nile Valley by 2340 BC.
Watermelon fruit is 91%water, contains 6% sugars, and is low infat(table).
In a100-gram (3+1⁄2-ounce) serving, watermelon fruit supplies 125 kilojoules (30 kilocalories) of food energy and low amounts ofessential nutrients(see table). Onlyvitamin Cis present in appreciable content at 10% of theDaily Value(table). Watermelon pulp containscarotenoids, includinglycopene.
Theamino acidcitrullineis produced in watermelonrind.
A number of cultivar groups have been identified:
(syn.C. lanatussubsp.lanatusvar.citroides;C. lanatusvar.citroides;C. vulgarisvar.citroides)
DNA data reveal thatC. lanatusvar.citroidesBailey is the same as Thunberg's bitter wooly melon,C. lanatusand also the same asC. amarusSchrad.  It is not a form of the sweet watermelonC. vulgarisnor closely related to that species.
Thecitron melonormakataan– a variety with sweet yellow flesh that is cultivated around the world for fodder and the production of citron peel andpectin.
(syn.C. lanatusvar.caffer)
C. cafferSchrad. is a synonym ofC. amarusSchrad.
The variety known astsammais grown for its juicy white flesh. The variety was an important food source for travellers in theKalahari Desert.
Another variety known askarkoerorbitterboelais unpalatable to humans, but the seeds may be eaten.
A small-fruited form with a bumpy skin has caused poisoning in sheep.
This is Linnaeus's sweet watermelon; it has been grown for human consumption for thousands of years.
This West African species is the closest wild relative of the watermelon. It is cultivated for cattle feed.
Additionally, other wild species have bitter fruit containingcucurbitacin.C. colocynthis(L.) Schrad. ex Eckl. & Zeyh.,C. rehmiiDe Winter, andC. naudinianus(Sond.) Hook.f.
The more than 1,200cultivarsof watermelon range in weight from less than1 kilogram (2+1⁄4pounds) to more than 90 kg (200 lb); the flesh can be red, pink, orange, yellow or white.
Charles Fredrick Andrus, a horticulturist at theUSDAVegetable Breeding Laboratory inCharleston, South Carolina, set out to produce a disease-resistant and wilt-resistant watermelon. The result, in 1954, was "that gray melon from Charleston". Its oblong shape and hard rind made it easy to stack and ship. Its adaptability meant it could be grown over a wide geographical area. It produced high yields and was resistant to the most serious watermelon diseases:anthracnoseandfusarium wilt.
Others were also working on disease-resistant cultivars; J. M. Crall at the University of Florida produced 'Jubilee' in 1963 and C. V. Hall of Kansas State University produced 'Crimson Sweet' the following year. These are no longer grown to any great extent, but their lineage has been further developed intohybridvarieties with higher yields, better flesh quality and attractive appearance.Another objective of plant breeders has been the elimination of the seeds which occur scattered throughout the flesh. This has been achieved through the use oftriploidvarieties, but these are sterile, and the cost of producing the seed by crossing atetraploidparent with a normaldiploidparent is high.
As of 2017, farmers in approximately 44 states in the United States grew watermelon commercially, producing more than $500 million worth of the fruit annually.Georgia, Florida, Texas, California and Arizona are the United States' largest watermelon producers, with Florida producing more watermelon than any other state.This now-common fruit is often large enough that groceries often sell half or quarter melons. Some smaller, spherical varieties of watermelon—both red- and yellow-fleshed—are sometimes called "icebox melons".The largest recorded fruit was grown inTennesseein 2013 and weighed 159 kilograms (351 pounds).
Watermelon is a sweet, commonly consumed fruit of summer, usually as fresh slices, diced in mixedfruit salads, or as juice.Watermelon juice can be blended with other fruit juices or made intowine.
The seeds have a nutty flavor and can be dried and roasted, or ground into flour.Watermelon rinds may be eaten, but their unappealing flavor may be overcome bypickling,sometimes eaten as avegetable,stir-friedorstewed.
Citrullis lanatus, varietycaffer, grows wild in theKalahari Desert, where it is known astsamma.The fruits are used by theSan peopleand wild animals for both water and nourishment, allowing survival on a diet of tsamma for six weeks.
The watermelon is used variously as asymbol of Palestinian resistance,of the Kherson regionin Ukraine, and ofeco-socialism, as in 'green on the outside, red on the inside'. Because it is mostly water, the watermelon has been used to symbolizeabrosexuality, a "fluid" or changing sexual orientation.In the United States, the watermelon has also been used asa racist stereotypeassociated withAfrican Americans.
Watermelons are plants grown from tropical to temperate climates, needing temperatures higher than about 25 °C (77 °F) to thrive. On a garden scale, seeds are usually sown in pots under cover and transplanted into the ground. Ideal conditions are a well-drained sandy loam with a pH between 5.7 and 7.2.
Major pests of the watermelon includeaphids,fruit flies, androot-knot nematodes. In conditions of high humidity, the plants are prone toplant diseasessuch aspowdery mildewandmosaic virus.Some varieties often grown in Japan and other parts of theFar Eastare susceptible tofusarium wilt.Graftingsuch varieties onto disease-resistantrootstocksoffers protection.
TheUS Department of Agriculturerecommends using at least onebeehiveper acre (4,000 mper hive) forpollinationof conventional, seeded varieties for commercial plantings. Seedless hybrids have sterile pollen. This requires plantingpollinizerrows of varieties with viable pollen. Since the supply of viable pollen is reduced, and pollination is much more critical in producing theseedlessvariety, the recommended number of hives per acre increases to three hives per acre (1,300 mper hive). Watermelons have a longer growing period than other melons and can often take 85 days or more from the time of transplanting for the fruit to mature.Lack of pollen is thought to contribute to "hollow heart" which causes the flesh of the watermelon to develop a large hole, sometimes in an intricate, symmetric shape. Watermelons suffering from hollow heart are safe to consume.
Farmers of theZentsujiregion of Japan found a way to growcubicwatermelons by growing the fruits in metal and glass boxes and making them assume the shape of the receptacle.The cubic shape was originally designed to make the melons easier to stack and store, but these "square watermelons" may be triple the price of normal ones, so appeal mainly to wealthy urban consumers.Pyramid-shaped watermelons have also been developed, and anypolyhedralshape may potentially be used.
Watermelons, which are calledtsammainKhoisan languageandmakataaninTswana language, are important water sources inSouth Africa, theKalahari Desert, andEast Africafor both humans and animals.
In 2020, global production of watermelons was 101.6 milliontonnes, with China (mainland) accounting for 60% of the total (60.1 million tonnes).Secondary producers includedTurkey,India,Iran,AlgeriaandBrazil– all having annual production of 2–3 million tonnes in 2020.