Sweet Potato Crop: by Cameron Lee

Native to Central and South America, the sweet potato is one of the world’s most important crops. Versatile, the sweet potato can be used in numerous applications. Famous chemist and botanist, George Washington Carver, a Missouri-born agricultural scientist, and innovator were able to discover a little over a hundred uses ranging anywhere from flour, starch, sugar, molasses, to stains, dyes, paints, and even medicine. Regarded as the world’s fifth most important crop, they can be enjoyed in a variety of ways, whether boiled, baked, or fried. Although high in starch like many grains and root crops around the world, it is also very rich in nutrients allowing it to serve as both a staple crop and vegetable (something pretty rare in the world of crops).  Therefore, multiple ethnic groups across the world have made the crop a staple in their cuisines. Although not widely known, the greens of the sweet potato are edible and very nutritious and widely used in some Southeast Asian and New Guinean cultures. 

The sweet potato is enjoyed around the world by many different cultures from Africa, Asia, and America. In Africa, particularly West African countries, the young leaves and vine tips are frequently consumed as a vegetable. In Egypt, the tubers of the sweet potatoes are known as “batatas” (بطاطا) and are common to see street vendors selling the crop. At times being baked as a snack or dessert, they are typically coated in honey. In East Asia, roasted sweet potatoes are quite popular. China typically has the yellow cultivars which are baked in a large iron drum and are also sold by street vendors. In Korea, the starch is used to make naengmyeon (cellophane noodles), even using sweet potatoes as a pizza topping. In the United States, sweet potatoes are mostly featured on Thanksgiving, but sweet potato fries among other uses have been gaining more popularity in recent years. 

There are three broad categories of sweet potatoes grown across the world.  There is a white starchy kind similar to potatoes, a hard, dry yellow kind, and the moist, sweet, and dark orange kind that is popular in the U.S., which is confused with the yam. Although sweet potatoes are commonly referred to as yams in North America, the sweet potato is a part of a different plant family. Yams are a part of the Dioscoridae family, which were domesticated in West Africa, whereas the sweet potato was domesticated in Western South America.  This confusion between the sweet potato and yams happened before the Civil War. Ships that brought West African slaves over to the United States via the Trans-Atlantic slave trade carried crops native to Africa as food for the long voyage. The crops included an African species of rice and other grains, okra, yams, and various kinds of beans and peanuts. The word yam is of West African origin with two languages having similar pronunciations of the word. In Fulani, yams translate to nyami meaning “to eat,” and in Twi, it translates to anyinam. Seeing that the two are relatively similar to one another, the West African slaves continued to use yams as the name for sweet potatoes. 

Sweet potato vines can grow up to nine to ten feet at a relatively fast rate, and although it is a perennial in the tropics, it will not survive our winters here and therefore is grown as an annual crop. A hermaphrodite, the plant has both male and female reproductive organs. Although sweet potatoes are pretty adaptable plants, they grow best in light and medium soils that are well-drained and require full sun for best yield. Its leaves can grow up to 10 centimeters and are typically heart- or egg-shaped with unlobed and sometimes toothed-margins. In late summer they produce pale purple or white trumpet-shaped flowers similar to a morning glory up to seven centimeters long and is often darker in color inside the tube. They grow in both tropical and temperate regions that experience hot summers. Due to its need for warmer climates, they have become a staple across Asia and Africa. When cooked, the sweet potato is sweet and highly rich in nutrients with some varieties having softer skins while the dryer white and yellow types are bred for their high starch content. When it comes to storing, if handled gently and left unwashed, the sweet potato can last for several months. They should not be stored in refrigerators as they can develop an off-taste and a hard core in the center. For preparation, the sweet potato should only be washed right before cooking because moisture can promote spoilage.

There are several theories about the sweet potato and its journey across the Pacific. According to findings from the Proceedings of the National Academy of Sciences, suggests that ancient Polynesians may have interacted with people living in South America before European contact. Archaeologists have hypothesized that ancient samples found in Polynesia around 1000 to 1100 CE originated from the western coast of South America. Pat Kirch, an archaeologist at the University of Berkeley, believes that the ancient Polynesians had the technology required to make the long ocean voyage across the Pacific to South America. They were great navigators of water, and in more recent years, further evidence has accumulated that the ancient Polynesians had made landfall in South America at some point. Making the voyage in large, sophisticated, double-hulled canoes which had the capability of carrying eighty or more people and was large enough to be out at sea for months. A linguistic link between the ancient Polynesians and the ancient South Americans seems to affirm the theory about the sweet potato’s movement across the Pacific as sweet potatoes have been found in Hawaii to Easter Island to New Zealand. The Uto-Aztecan word camotli seems to be the root of all words found across the Pacific. This evidence indicates that the center of domestication for the plant located in western South America.

Further theories have emerged as some believe that the sweet potato was deliberately or accidentally put on a boat that drifted across the Pacific, although both scenarios may seem unlikely, they are plausible. Ocean currents like the Humboldt current are slow and sluggish compared to the Gulf Stream, with cold water from Antartica flowing up the coast of South America where it dissipates and eventually flows towards the west. A third theory is that the sweet potato was first brought to Europe and then later introduced to Asia following Columbus’ expedition in 1492. Later continuing its journey eastward through the Silk Road, when explorers arrived in Polynesia in the eighteenth century, the sweet potato was already ingrained in their culture. However, the crop would not be identified by European explorers until the Spanish explorer Hernando de Soto made landfall in South America. Tradition states that the Spanish explorers were the first to introduce South America’s native sweet potato and the white potato to the rest of the world; with its westward journey across the Pacific guided by Portuguese voyagers arriving at the Philippines and the East Indies. However, this theory tends to be Euro-centric and discounts the maritime capabilities of the ancient Polynesians who were even able to colonize Madagascar, later becoming the Malagasy people. 

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Coe, Sophie D. America’s First Cuisines. University of Texas Press, 2015.

Bryant, Alice, and Ashley Thompson. “Many Food Names in English Come From Africa.” VOA. February 12, 2018. Accessed July 11, 2019. 


“Ipomoea Batatas (L.) Lam.: Plants of the World Online: Kew Science.” Plants of the World Online. Accessed July 02, 2019. http://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:1101088-2.

Cantaluppi, Carl, and Gwen Rubio. “Sweet Potato History-Did You Know?” NC Cooperative Extension News. Accessed July 02, 2019. https://granville.ces.ncsu.edu/2013/09/sweet-potato-history-did-you-know-2/.

 Doucleff, Michaeleen. “How The Sweet Potato Crossed The Pacific Way Before The Europeans Did.” Food History and Culture. January 23, 2013. Accessed July 02, 2019. https://www.npr.org/sections/thesalt/2013/01/22/169980441/how-the-sweet-potato-crossed-the-pacific-before-columbus.

“Who Are the Malagasy?” Exploring Madagascar, a Land of Cultural and Biological Richness. Accessed July 02, 2019. https://www.wildmadagascar.org/overview/FAQs/who_are_Malagasy.html.