The sweet potato is native to Central America, but may have spread to Polynesia before the arrival of the Europeans. The Spanish brought the sweet potato to the Philippines and the East Indies; the Portuguese took it to India, Asia and Malaysia. When Columbus and his shipmates ate their first boiled sweet potatoes, they compared the taste to that of chestnuts. Attempts to introduce them to Europe were unsuccessful, because the climate was not right for cultivation, and the sweet potato is still almost unknown there. It did not reach European tables from Spain voluntarily. In fact, Spanish gardeners fanatically kept the secret of its growth. Henry VIII, whose first wife, Catherine of Aragon, was Spanish, received the sweet potato as part of her dowry and liked the flavor so much that he insisted that Spain export them to England, which they did with some lack of enthusiasm. The king venerated them and, renowned for his appetite, was able to eat two dozen per meal. His palate was so committed to what he called "the Spanish potato" that, after his divorce from Catherine, he gave a prize of land and gold to the gardener who could grow them in Britain. The motivation worked, and by the mid-16th century, sweet potatoes bloomed all over the British Isles - but the rage was short-lived, most likely because they need a warmer climate to survive. All the plants withered in a typically wet and cool English summer and never grew there again.
In Asia, sweet potatoes are so commonplace, they're often called Japanese potatoes. Early settlers in America quickly adopted them, serving them as a staple for livestock as well as humans. It's said that sweet potatoes helped the South survive during the Civil War and the Reconstruction.
The sweet potato is remarkable for its 3 to 6 percent sugar content, which increases when it's stored at warm temperatures and during the early stages of the cooking process, because enzymes break down the starch into glucose. The sweet potato provides more calories, minerals and vitamin A, but less protein, than the white potato. The leaves are also edible.
From The Food Encyclopedia by Jacques Rolland and Carol Sherman
