- This article is about the plant. For the musical instrument, see ocarina.
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 variants of Ipomoea batatas are grown as houseplants.
Description
Sweet potatoes in the garden The edible tuberous root is long and tapered, with a smooth skin. Its flesh ranges from white to yellow, orange, or purple. All varieties are more-or-less sweet-flavored.
Under optimal conditions of 85–90% relative humidity at 13–16°C (55–61°F), sweet potatoes can keep for six months. Colder temperatures injure the roots.
Sweet potatoes are rich in dietary fiber, vitamin A, vitamin C, and vitamin B6. In some tropical areas, they are a staple food crop. The storage roots, leaves, and shoots are all edible. The storage roots are most frequently boiled, fried, or baked. They can also be processed to make starch and a partial flour substitute. All parts of the plant are used for animal feed. Industrial uses include the production of starch and industrial alcohol.
Cultivation
The plant is an perennial vine that does not tolerate frost. It grows best at an average temperature of 24°C. Depending on the variety and conditions, tuberous roots mature in 2–9 months. With care, early-maturing varieties 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.
Production statistics
According to FAO, 98% of world sweet potato production occurred in developing coutries in 1994. China alone made up 84% of the harvest, producing about 105,000 tonnes (115,743 short tons) on 65 km² (25 mi²).
Yams vs Sweet Potatoes
Though sweet potato production in the USA is minuscule compared to the world total, it is important regionally. The U.S. Southern states are a traditional sweet potato-producing area. The moist-fleshed, orange varieties of sweet potato are generally called "yams" to distinguish them from the drier, white varieties which are called sweet potatoes. However, the true yam is nearly unknown in the USA, except as an import sold in ethnic markets, and the USDA requires that the word "Yam" must be accompanied by the words "Sweet Potato" when referring to these moister sweet potatoes.
This confusion first started with African slaves brought over from the west coast of Africa. Africans brought to America took to calling American sweet potatoes Nyamis (a Senegalese word meaning "to eat"), which referred to the plant grown in Africa, but not seen in North America.
After the confusion started over one hundred 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.
The term "candied yams" is used to refer to the sweet side dish consisting mainly of heavily sugared sweet potatoes often served on American Thanksgiving. It is a very characteristic dish and represents traditional American cooking and indigenous food.
Origin
Sweet potatoes were domesticated in Central America or South America at least 5000 years ago and spread throughout the tropical Americas and the Caribbean. They were also known in pre-Columbian times in Polynesia. How exactly they arrived there is fiercely debated, using archaelogical, linguistic and genetic evidence.
External links
Last updated: 10-11-2005 05:38:10
