The watermelon is an annual that has a prostrate or climbing habit. Stems are up to 10 feet long and new growth has yellow or brown hairs. Leaves are 2+1⁄4 to 7+3⁄4 inches long and 1+1⁄2 to 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 genus Citrullus, watermelon has branching tendrils. Plants have unisexual male or female flowers that are white or yellow and borne on 1+1⁄2 in hairy stalks. Each flower grows singly in the leaf axils, and the species’ sexual system, with male and female flowers produced on each plant. The male flowers predominate at the beginning of the season; the female flowers, which develop later.
The large fruit is a kind of modified berry called a pepo with a thick rind and fleshy center. Wild plants have fruits up 8 inches in diameter, while cultivated varieties may exceed 24 inches. The rind of the fruit is mid- to dark green and usually mottled or striped, and the flesh, containing numerous pips spread throughout the inside, can be red or pink (most commonly), orange, yellow, green or white.
Watermelons were originally cultivated for their high water content and were stored to be eaten during dry seasons, not only as a food source, but as a method of storing water. Watermelon seeds were found in the Dead Sea region.
Early watermelons were not sweet, but bitter, with yellowish-white flesh and difficult to open. Through the process of breeding, watermelons later tasted better and were easier to open.
European colonists and slaves from Africa introduced the watermelon to the New World. Spanish settlers were growing it in Florida in 1576, and it was being grown in Massachusetts by 1629, and by 1650 was being cultivated in Peru, Brazil and Panama. Around the same time, Native Americans were cultivating the crop in the Mississippi valley and Florida. Watermelons were rapidly accepted in Hawaii and other Pacific islands when they were introduced there by explorers such as Captain James Cook. In the Civil War era United States, watermelons were commonly grown by free black people and 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 racist stereotype where black people shared a supposed voracious appetite for watermelon, a fruit long correlated with laziness and uncleanliness.
Seedless watermelons were initially developed in 1939 by Japanese scientists who were able to create seedless hybrids which remained rare initially because they did not have sufficient disease resistance. Seedless watermelons became more popular in the 21st century, rising to nearly 85% of total watermelon sales in the United States in 2014.
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