Ipomoea batata

The sweet potato*, Ipomoea batata*, is a species of edible morning glory native to northern South America. It was first domesticated by Native Americans who cultivated it primarily for its large, starchy root (though the leaves are also edible) around 5000 years ago. Around 1000 BCE, Polynesians visited Central or South America, and took sweet potatoes back with them to the Cook Islands.

With the conquest of the New World by the Spanish in the 1500s and 1600s, the sweet potato was introduced into the Old World via Spanish and Portuguese merchants. There, the sweet potato quickly became a popular and hardy (albeit frost-intolerant) crop in virtually all warm regions of the world with enough water to spare for its cultivation. The sweet potato’s hardiness is one of the main reasons behind its popularity in Polynesia, as it is capable of surviving flooding caused by constant typhoons.

In Asia, the sweet potato is a ubiquitous vegetable crop grown for consumption by both humans and livestock (usually pigs). The starchy tubers are usually boiled, or roasted, occasionally fried. The starch is also used to make flour. In Korea, the starch is used for making cellophane noodles. The stems and leaves can be boiled and eaten as a potherb, though in the Philippines, the plant portions are fed to pigs as fodder. In China, all parts of the plant are fed to pigs to speed and enhance their growth (about half of the 105 million metric tons’ worth of the country’s annual national growth is set aside for animal feed).

The sweet potato is an extremely nutritious plant that nourishes the blood, eyes, and bones thanks directly to its high starch contents, high amounts of Vitamins A, B, B2, and C, and large amounts of minerals such as Calcium (present in both the leaves and the roots). The roots are a good source of soluble long dietary fibers, helping to maintain intestinal regularity. In many parts of Asia, especially in warmer regions with a strong Buddhist presence, sweet potatoes are used as a dietary source of protein.

There are numerous varieties of sweet potatoes of differing root colors, and differing root textures. The most commonly seen are yellow-fleshed and orange-fleshed varieties seen for sale in supermarkets. Orange-fleshed sweet potatoes are more nutritious if only because they contain more beta-carotene. Purple sweet potatoes, often confused with the purple or winged yam, are commonly grown in Southeastern Asia, and are sometimes seen for sale in the West in Oriental-themed supermarkets.

Sweet potato roots should be stored in a cool, dry place, ideally around 35 to 42 degrees Fahrenheit to prevent the roots from sprouting (usually for at least one to two weeks after purchase). A dry drawer in the refrigerator makes an ideal storage place. However, unlike true potatoes, if the root begins sprouting, the sweet potato still remains edible, as the whole plant is nontoxic. If the root begins sprouting, one should simply cut the sprouts off with the peel, then eat the root as soon as possible. A root that sprouts while in storage means that that particular root is an exceptionally healthy individual.

The sweet potato is often confused with the true yams of the genus *Discorea*, especially the white yam, *D. rotundata*, the yellow yam, *D. cayenensis*, and the winged yam, *D. alata*. Botanically, yams are monocot vines, often erroneously stated to be related to the lilies, but actually related to the asphodel and colicroot, while sweet potatoes are a species of morning glories. Culinarily, yams and sweet potatoes are extremely similar; to the point of being interchangeable, but the flesh of yams tend to be drier and starchier.

In Chinese food therapy, the sweet potato nourishes the Spleen, promotes blood and circulatory health, and encourages formation of bone. Sweet potato also relieves irritatibility due to upset stomach, and can help promote regularity of bowel movement. Sweet potato is a nutrient-dense food and can easily treatments malnourishment.