Sweet potato
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? Sweet
Potato |
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 Sweet potato in
flower
Hemingway, South Carolina |
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| Ipomoea
batatas Linnaeus |
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The sweet potato (Ipomoea batatas) is a crop plant whose large, starchy, sweet-tasting tuberous roots are an important root vegetable. The young leaves and shoots are sometimes eaten as greens. The sweet potato is only distantly related to the potato (Solanum tuberosum). Although the sweet potato is sometimes known as yam in the United States, it is unrelated to the botanical yam.
The genus Ipomoea that contains the sweet potato also includes several garden flowers called morning glories, though that term is not usually extended to Ipomoea batatas. Some cultivars of Ipomoea batatas are grown as houseplants.
The plant is a herbaceous perennial vine, bearing alternate heart-shaped or palmately lobed leaves and medium-sized sympetalous flowers. The edible tuberous root is long and tapered, with a smooth skin whose colour ranges between red, purple, brown and white. Its flesh ranges between white, yellow, orange, and purple.
Origin and distribution
Sweet potatoes are native to the tropical Americas and were domesticated there at least 5000 years ago. [1] [2] They spread very early throughout the region, including the Caribbean. They were also known in pre-Columbian times in Polynesia. How exactly they arrived there is the subject of a fierce debate which involves archaeological, linguistic and genetic evidence.
Sweet potatoes are now cultivated throughout tropical and warm temperate regions wherever there is sufficient water to support their growth.
According to 2004 FAO statistics world production is 127,000,000 tonnes [3]. The majority comes from China with a production of 105,000,000 tonnes from 49,000 km². Almost half of the Chinese crop is used for livestock feed [4].
Per-capita production is greatest in countries where sweet potatoes are a staple of human consumption, led by the Solomon Islands at 160 kg per person per year and Burundi at 130 kg.
North Carolina is the leading U.S. state in sweet potato production. Currently, North Carolina provides 40% of the annual U.S. production of sweet potatoes.
The town of Benton, Kentucky, celebrates the sweet potato annually with its Tater Day Festival on the first Monday of April.
Cultivation
The plant does not tolerate frost. It grows best at an average temperature of 24 °C. Depending on the cultivar and conditions, tuberous roots mature in 2 to 9 months. With care, early-maturing cultivars can be grown as an annual summer crop in temperate areas, such as the northern USA. Sweet potatoes rarely flower when the daylight is longer than 11 hours, as is normal outside of the tropics. They are mostly propagated by stem or root cuttings or by adventitious roots called "slips" that grow out from the tuberous roots during storage. True seeds are used for breeding only.
Under optimal conditions of 85 to 90 % relative humidity at 13 to 16 °C (55 to 61 °F), sweet potatoes can keep for six months. Colder temperatures injure the roots.
Uses
Although the leaves and shoots are also edible, the starchy tuberous roots are by far the most important product. In some tropical areas, they are a staple food-crop. Besides starch, they are rich in dietary fiber, vitamin A, vitamin C, and vitamin B6. All cultivars are more-or-less sweet-flavored.
The roots are most frequently boiled, fried, or baked. They can also be processed to make starch and a partial flour substitute. Industrial uses include the production of starch and industrial alcohol.
Candied sweet potatoes are a sweet side dish consisting mainly of heavily sweetened potatoes often served on American Thanksgiving. It is a very characteristic dish and represents traditional American cooking and indigenous food.
All parts of the plant are used for animal feed.
They can also be sliced and fried, and eaten just like potato chips.
Names
The moist-fleshed, orange cultivars of sweet potato are occasionally referred to as "yams". One explanation of this confusion is that it started with African slaves brought over from the west coast of Africa. Africans brought to America took to calling American sweet potatoes Nyamis, perhaps from the Fulani word nyami (to eat) or the Twi word anyinam, which refers to a true yam. The true yam, which is native to Africa and Asia, can grow up to 2 m (6 ft) in length (sometimes with knuckle-like ends) and has a scaly skin, a pinkish white center, and a thick, almost oily feel to the tongue.
After the confusion started over 100 years ago, many farmers and stores began marketing American-grown sweet potatoes as yams; the name stuck. In more recent times there has been an effort to stop the use of "yam" for sweet potatoes, but this has only been partially successful. USDA branding regulations require the word "Yam" to be accompanied by the words "Sweet Potato" when referring to these moister sweet potatoes.
Starchy, white-fleshed types are sometimes called batatas or boniatos, from dialectal Spanish terms which in Spanish refer generically to all types of sweet potato. The more specific meaning in English derivestion in some English-speaking regions between the starchy types and Spanish-speaking Caribbean immigrants.
Substratum names used in local varieties of English include kumara (from Māori) in New Zealand, and to some degree camote (from Spanish) in the southwestern United States.