“What’s in a name?” Well, sometimes a good bit of confusion—take yams and sweet potatoes, for example. If you’re in the United States and you’re calling something a yam, odds are you’re talking about a sweet potato, in which case, you’re wrong. Sweet potatoes are members of the morning glory family. Yams, on the other hand, are the tuberous roots of climbing plants of the genus Dioscorea. The two are entirely unrelated. Yet in parts of the U.S., the habit persists of calling sweet potatoes yams.
This confusion is perhaps as understandable as it is longstanding. Both the yam and the sweet potato began to come into use in Europe at about the same time (around 500 years ago), though the yams arriving on the continent came primarily from Africa and Asia, while the sweet potatoes were coming from the Caribbean and South America. Also, if you don’t see the plants growing, you might confuse one tuberous root for the other. Once dug up, sweet potatoes and yams can look quite a bit alike. (Well, some species of yam look like sweet potatoes. Some yam species grow to immense sizes—up to 100 pounds—and would never be confused with sweet potatoes.) The difficulty came from a wide range of new foods all being introduced at the same time, and everyone trying to figure out what to call them—similar to chilies being named peppers by confused Spanish explorers.
In fact, the word for yam came into English from the Portuguese inhame and Spanish ñame. The Portuguese and Spanish were the people most responsible during the late 1400s for seeking sea routes to the exotic taste treats of the world, for trying to label the new items being discovered, and for spreading both labels and foods. The Portuguese picked up the word in Africa, actually through a misunderstanding. Having asked what Africans in Guinea were digging up, they thought the response identified the plant, but in reality, nyami means “something to eat.” So the explorers picked up a word that wasn’t a plant name at all and applied it to all sorts of plants that weren’t the original plant. So one might argue that sweet potatoes are yams, because they are something to eat, but that would be stretching the point.
Sweet potatoes (but not yams) are among the numerous foods indigenous to the New World that sped around the globe during the Age of Exploration, dramatically altering the world’s patterns of consumption. Though Columbus would never have seen a white potato, he was quick to discover the sweet potato. He was served three or four different kinds of sweet potato at a feast given by the king of the island of Saint Thomas, and was impressed with their size and variety. Columbus and his crew found sweet potatoes on the menu on most islands, with a wide variety of names. In Arawak (Taino dialect, to be precise), it was called batatas, which eventually evolved into our word potato. The original term is still reflected in the plant’s scientific name, Ipomoea batatas.
All species of sweet potato are indigenous to the New World. They were widely cultivated in the tropical and semi-tropical regions of South America, especially Peru, by 750 BC. They then spread to Central America and the Caribbean. Sweet potatoes were growing in Spain as soon as Columbus got home with some plants. The Spanish loved the sweet potato—preferred it, in fact, to the white potato, when that arrived a while later. Popularity in the rest of Europe, however, grew somewhat unevenly. Best suited to warmer climates, the sweet potato was most easily grown in Spain, Portugal, and Italy, and these were where it enjoyed its greatest European successes.
Henry VIII is said to have enjoyed sweet potatoes. He, and the rest of England, initially obtained their sweet potatoes from Spain, and the British called them Spanish potatoes. In 1564, Sir John Hawkins returned from a voyage to South America, bringing England its first shipment of sweet potatoes directly from the New World. They were written up in herbal guides, and even merited a few mentions in Shakespeare. Of course, William just refers to them as potatoes—it wasn’t until 1775 that they became known as sweet potatoes, with “potato” alone coming to mean a white potato. (Even today, Webster’s Third International Dictionary defines “potato” first as sweet potato and second as white potato.)
Louis XV and, later, Napoleon’s Josephine, created brief interest in the sweet potato in France. However, a sweet vegetable did not appeal greatly to the French palate, and when it was no longer fashionable among the royals, it was quickly dropped from the menu.
The sweet potato is not now grown or used in any particularly significant quantities in most of Europe (Russia being the primary exception). However, its popularity exploded, and remains high, in Africa, the Pacific Islands, and much of Asia, and it is still popular in its native Latin America. In fact, because of its tremendous popularity in these regions, the sweet potato is considered one of the fifteen most important food crops in the world.
The Spaniards had the sweet potato with them when they arrived in the Philippines in 1521. It was instantly popular and quickly spread to other islands, carried by the Portuguese. It soon became a staple throughout the Pacific. Among Papuans in New Guinea, it is reported to make up nearly 90 percent of the diet.
It seems likely that China received the sweet potato from Spanish traders, too, possibly by way of the Philippines. However it arrived, the sweet potato was well established in China by the end of the 16th century, and they are still widely consumed. In cities and villages in China, I have often seen sweet potatoes roasting over hot coals on street vendors’ food carts or being eaten out of hand by hurrying lunchtime crowds. There are those who say that China was able to support a larger population with the sweet potato than it could have without it. Though sweet potatoes are popular in tropical regions worldwide, China grows most of the world’s crop.
From China, the sweet potato moved to Japan, where it became not only a food source, but also a source of starch and alcohol. It is now the third most important food crop in Japan.
Portuguese traders also carried the sweet potato to India, which may surpass even China in appreciation of the tuber. Sweet potatoes, which reached the subcontinent by at least 1616, are now cultivated in almost all parts of India. Africa, too, likely got sweet potatoes from the Portuguese, not as a gift, but as cheap food for slaves. It was African slaves who had the greatest hand in nurturing sweet potatoes in the American South, and it was a freed slave who, after the Civil War, helped promote them. George Washington Carver, the brilliant agricultural scientist who joined Booker T. Washington at the Tuskegee Institute, was researching crops that could reduce malnutrition and increase income in the South. He did research and wrote articles about sweet potatoes, and created numerous recipes. He hoped that sweet potatoes, along with pecans and peanuts, could replace cotton as the region’s primary cash crops. Today, in the U.S., other than at Thanksgiving, the primary consumption of sweet potatoes is still in the South.
Sweet potatoes are remarkable for their sugar content—3 percent to 6 percent. They have more minerals than white potatoes, but have less protein. In addition, the more brightly colored varieties (the numerous species of sweet potato range from almost white through orange, red, and even purple) are high in vitamin A (as beta carotene). They are also a tremendously good source fiber. However, they do not store as well as white potatoes, so only buy what you need, when you’re cooking with them. They are wonderful simply roasted and served with a little butter or mashed with butter or broth and a sprinkle of cinnamon. They make lovely soup, as well, and sweet potato pie is a Southern classic. So enjoy this international staple all winter—just don’t call it a yam.
© 2009 Cynthia Clampitt
This article originally appeared in a slighty different form in Hungry Magazine.