Succulent fruit of Citrullus lanatus (formerly C. vulgaris), in the gourd family, native to tropical Africa and cultivated on every continent except Antarctica. The vines spread across the ground with branched tendrils, deeply cut leaves, and light-yellow flowers. Each vine bears 2–15 large, reddish, white, or yellow, sweet, very juicy fruits with flat black seeds. Varieties differ in flesh color, shape, and rind thickness. The rind may be preserved as a pickle.
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It is not known when the plant was first cultivated, but Zohary and Hopf note evidence of its cultivation in the Nile Valley from at least as early as the second millennium BC. Finds of the characteristically large seed are reported in Twelfth dynasty sites; numerous watermelon seeds were recovered from the tomb of Pharaoh Tutankhamun, although the existence of the fruit in ancient Egypt is not certain because it is not depicted in any hieroglyphic text nor does any ancient writer mention it. It wasn't present in any other culture of the ancient Mediterranean.
By the 10th century AD, watermelons were being cultivated in China, which is today the world's single largest watermelon producer. By the 13th century, Moorish invaders had introduced the fruit to Europe; and, according to John Mariani's The Dictionary of American Food and Drink, "watermelon" made its first appearance in an English dictionary in 1615.
In Vietnam, legend holds that watermelon was discovered in Vietnam long before it reached China, in the era of the Hùng Kings. According to legend, watermelon was discovered by Prince Mai An Tiêm, an adopted son of the 11th Hùng King. When he was exiled unjustly to an island, he was told that if he could survive for six months, he would be allowed to return. When he prayed for guidance, a bird flew past and dropped a seed. He cultivated the seed and called its fruit "dưa tây" or western melon, because the birds who ate it flew from the west. When the Chinese took over Vietnam in about 110 BC, they called the melons "dưa hảo" (good melon) or "dưa hấu", "dưa Tây", "dưa hảo", "dưa hấu"—all words for "watermelon". An Tiêm's island is now a peninsula in the suburban district of Nga Sơn.
Museums Online South Africa list watermelons as having been introduced to North American Indians in the 1500s. Early French explorers found Native Americans cultivating the fruit in the Mississippi Valley. Many sources list the watermelon as being introduced in Massachusetts as early as 1629. Southern food historian John Egerton has said he believes African slaves helped introduce the watermelon to the United States. Texas Agricultural Extension horticulturalist Jerry Parsons lists African slaves and European colonists as having distributed watermelons to many areas of the world. Parsons also mentions the crop being farmed by Native Americans in Florida (by 1664) and the Colorado River area (by 1799). Other early watermelon sightings include the Midwestern states (1673), Connecticut (1747), and the Illiana region (1822).
Until the 1940s, however, it was hard to find watermelons in good condition at grocery stores. Melon lovers had to grow their own, which tended not to keep for long, purchase them from local grocers supplied by truck farmers, or purchase them from roadside produce stands. Now they can be found in most local grocery stores, and if preferred in slices or whole, with seeds or without.
Charles Fredric Andrus, a horticulturist at the USDA Vegetable Breeding Laboratory in Charleston, South Carolina, set out to produce a disease-resistant and wilt-resistant watermelon. The result 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: anthracnose and fusarium wilt. Today, farmers in approximately 44 states in the U.S. grow watermelon commercially, and almost all these varieties have some Charleston Gray in their lineage. Georgia, Florida, Texas, California and Arizona are the USA's largest watermelon producers.
This now-common watermelon is often large enough that groceries often sell half or quarter melons. There are also some smaller, spherical varieties of watermelon, both red- and yellow-fleshed, sometimes called "icebox melons."
For commercial plantings, one beehive per acre (over 9,000 m² per hive) is the minimum recommendation by the US Department of Agriculture for pollination of conventional, seeded varieties. Because seedless hybrids have sterile pollen, pollinizer rows of varieties with viable pollen must also be planted. Since the supply of viable pollen is reduced and pollination is much more critical in producing the seedless variety, the recommended number of hives per acre, or pollinator density, increases to three hives per acre (1,300 m² per hive).
In Japan, farmers of the Zentsuji region found a way to grow cubic watermelons, by growing the fruits in glass boxes and letting them naturally assume the shape of the receptacle. The square shape is designed to make the melons easier to stack and store, but the square watermelons are often more than double the price of normal ones. Pyramid shaped watermelons have also been developed.
Fresh watermelon may be eaten in a variety of ways and is also often used to flavor summer drinks and smoothies.
Watermelon contains about six percent sugar by weight, the rest being mostly water. As with many other fruits, it is a source of vitamin C. It is not a significant source of other vitamins and minerals unless one eats several kilograms per day.
The amino acid citrulline was first extracted from watermelon and analysed. Watermelons contain a significant amount of citrulline and after consumption of several kg an elevated concentration is measured in the blood plasma, this could be mistaken for citrullinaemia or other urea cycle disorder. Watermelon rinds are also edible, and sometimes used as a vegetable. In China, they are stir-fried, stewed, or more often pickled. When stir-fried, the de-skinned and de-fruited rind is cooked with olive oil, garlic, chili peppers, scallions, sugar and rum. Pickled watermelon rind is also commonly consumed in the Southern US, Russia, Ukraine, Romania and Bulgaria. In Balkans, specially Serbia, watermelon slatko is also popular .
Watermelon seeds are rich in fat and protein, and are widely eaten as a snack, added to other dishes, or used as an oilseed. Specialized varieties are grown which have little watery flesh but concentrate their energy into seed production. In China watermelon seeds are one of the most common snack foods, competing with sunflower seeds, and sold roasted and seasoned. In West Africa, they are pressed for oil, and are popular in egusi soup and other dishes. There can be some confusion between seed-specialized watermelon varieties and the colocynth, a closely-related species with which they share many characteristics, uses, and similar or identical names.
Watermelon is 92 percent water by weight.
Watermelon is also mildly diuretic.
Watermelon with red flesh is a significant source of lycopene.
A traditional food plant in Africa, this fruit has potential to improve nutrition, boost food security, foster rural development and support sustainable landcare.
Some people also prepare and eat watermelon peel (i.e., rind).
There are more than twelve hundred varieties of watermelon ranging in size from less than a pound, to more than two hundred pounds with flesh that is red, orange, yellow, or white. Several notable varieties are included here.
Watermelons are used in many parts of the world as symbols and during various celebrations.