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Despite its name, the sweet potato is only very distantly related to the common potato. In addition, while a particular orange-colored variety of sweet potato is known as a yam in the United States, true yams belong to a different family of plants.
The sweet potato is a tuberous vegetable that grows on an herbaceous perennial vine with alternate heart-shaped or palmately lobed leaves. The flesh of the tuber may be white, orange, purple, pink, or any shade of these colors, with white-fleshed varieties being most common in Africa and Asia and orange-colored varieties most common in America. There about 400 sweet potato cultivars worldwide.
One of the oldest vegetables known to man, the sweet potato is native to Central and South America, where it has been consumed for at least 10,000 years and cultivated for at least 5,000 years. Sweet potatoes were in Polynesia by 1000 A.D., but whether they were taken there by South Americans visiting Polynesia or Polynesians who had been to South America is not known. Christopher Columbus took sweet potatoes back to Europe; Spanish explorers introduced them into the Philippines, and Portuguese explorers carried them into Africa, India, Indonesia and southern Asia. Sweet potatoes were a staple crop in many colonial American settlements; the orange-colored variety we know as the "yam" was introduced into the United States from Europe in the mid-20th century.
Sweet potatoes can grow in a variety of soils and soil conditions, but do best in slightly acidic soils with good drainage. They do not tolerate frost or drought, so are most commonly grown in tropical and warm temperate regions that recieve an average of 30-35 inches of rain a year. China is the world's largest producer of commercially-grown sweet potatoes, followed by Nigeria, Uganda, Indonesia, Vietnam, Tanzania, India, and Japan. North Carolina is the largest producer in the United States, followed by California, Louisiana, and Mississippi. Although they can be grown from seed, the vast majority of sweet potatoes are cultivated by cuttings that are started in a greenhouse and then transplanted into a field once the roots are established.
Sweet potatoes are rich in beta-carotene, vitamins A, B6 and C, calcium, manganese, and dietary fiber. There is some evidence to suggest that nutrients present in sweet potatoes may help prevent irritable bowel syndrome and other intestinal disorders. Sweet potatoes also possess some anti-inflammatory properties, with the levels of those properties being highest in the more vividly colored varieties.
This page was last updated on 02/18/2017.