Sweet Potatoes

Description Varieties Recipes

Three things made this spindly root of the morning glory family a New World treasure: sugary flavor, the gluttony it inspired in livestock, and its productivity in the field. Native to the American tropics, it came into cultivation approximately 5,000 years ago in Central America, and its culture spread through the West Indies and the lands rimming the Caribbean. Its wild ancestor grew in northern South America, but has all but disappeared supplanted by its domesticated offspring. (The “wild sweet potato” or “man of the woods” found in the American Midwest is a botanical cousin, not part of the direct lineage of the cultivated vegetable.)

While the culinary charm of the sweet potato inspired cultivators to grow it, its excellence as animal feed moved it from the garden to the field. John Lowell, one of the smartest agricultural experimenters in New England, counseled in 1823 that northern farmers take the plant up, regardless of its tropical origin. “It is preferred by all animals of whatever description. Cows and pigs eat it greedily, and even dunghill fowls will attack and consumer it in a raw state.”[1] Animals savored every part of the plant, leaves, stems, and roots. Producing 300 bushels of roots an acre, it proved more prolific than any other root vegetable grown for feed—mangel wurtzel, turnips, or potatoes. It averaged three times more nutrition per acre than corn. For this reason, it forms the foundation of 21st century Chinese feed agriculture.

Though about 70% of the root is water, the dry matter is nearly all carbohydrate. While the amounts of sugars, carotenoids, and amino acids differ among sweet potato varieties, the average values of dry matter are 70% starch, 10% sugar, 5% protein, 10% fiber, and 1 to 2 % lipid.[2] The starches undergo ready enzymic transformation into sugars; chopping the potatoes is enough to trigger the transformation, but cooking greatly aids the sweetening. When Jennifer Wolfe sampled various samples grown around the world, she found a variety from Louisiana boasting 38.3% sugar.

When Europeans first encountered the root in the 16th century, the starchiness of the sweet potato, as well as the Peruvian potato (what was later called the ‘Irish Potato’), greatly pleased its consumers. Their penchant for porridges, bread, and pasta led them to abandon the traditional European‘bread root,’ the asphodel, and consume the imports instead. Their hunger for starch caused experimenters to process the roots into “farinaceous matter’—sweet potato flour and sweet potato starch. These eventually would find their way into jellies, puddings, and quick breads.

Today a dozen varieties jostle for market dominance. Foremost in acreage and sales is the smooth-skinned orange Centennial. Three traditional varieties, all of which boast extraordinary sweetness, have maintained popularity over decades: the yellow fleshed mealy Nancy Hall favored by gardeners and bakers, the gold skinned, creamy white-fleshed Jersey, and the meaty reddish Puerto Rico. Southern Universities and agricultural stations have recently contributed numbers of new cultivars noteworthy for yield and resistance to insect pests: the Beauregard, the Carolina Bunch, the Covington, the Darby, the Jewel, the Regal, the Sumor, and the Vardaman. But the modern varieties are refractions of several ancestral types bred true in the early nineteenth century. These parent potatoes were designated at first by color names and geographical designations. In the north, the species tended to be called “Carolina Potato” in the first decades of the century, and then specified in terms of color: “the white are the earliest, and the best for our climate; then the yellow, and the red.”[3] There was in addition to this color differentiation a vernacular division of roots into sweet potatoes and yams, with spindly orange-fleshed roots being designated by the latter name. Dr. McChesney, a New Jersey planter with experience in the Leeward Islands in the West Indies observed in 1831, “I could find but little difference between their yams and sweet potatoes.”[4] His remark was probably just, for there may have been no botanical difference. In the New World the name yam came to be applied in to both the West African perennial herbaceous vine (Dioscorea) and to Ipomoea batatas, because the African Discorea cayenensis bore superficial resemblance to certain dark brown or yellow/orange skinned sweet potatoes.

The confusion of yams and sweet potatoes dates from European contact, when Columbus encountered sweet potatoes for the first time and conceived them to be a variety of yam—the edible West African tubers of the Dioscorea family had been well known to Europeans since the Portuguese voyages along the continent’s west coast in the 1460s and ‘70s. He brought examples to Europe from the second voyage. Yet African yams never established a substantial presence on the North American mainland. Sweet potatoes called yams did. When enslaved Africans encountered sweet potatoes in the West Indies, they processed them as they did the yams that they brought with them over the Atlantic. They did not eat them raw, as livestock were wont to do. They shredded, pounded, leached, boiled, roasted or fried them—the cooking processes designed to counteract the toxicity of the raw African yam. Though baking was not a West African culinary technique, contact with Europeans and their bread fixations taught West Indian slaves to bake the sweet potatoes into breads, pones, and pies.

Rev. Griffith Hughes Natural History of Barbados (1750) offers an early glimpse of the potato and its uses:

“These very useful Roots are distinguished in this Island from another into at least thirteen Sorts; but as this great Variety hath but very small real Difference, I shall therefore pass by these and less necessary Distinctions, and divide them into the white and red, the long and the round Sort. Each of these differs from the English Potato, by being propagated by a Slip or Vine, which they produce instead of upright Stalks. Another remarkable Difference is, that the West-India Potatoes have all a sweetish Taste; they are here look’d upon so beneficial, that there is scarce an Estate, where there is not a considerable Quantity of Land planted with them; for these with Yams and Plantain serve instead of Bread to most of the middling, and almost intirely to the poorer Sort; tho’ they are not quite destitute of a king of Bread, made with these Roots: For the Potatoes being first grated, and the Juice pressed out, the flowery or mealy Part is mix’d with Sugar and Spice, and made into Paste, which being baked in the Over, in the Form of a Plum-cake, its Taste is far from being disagreeable; this they call Pone. With the express’d Liquor of either the red or the white Potato is made what we here call Moby, or a Sort of cool Drink, answering to small Beer in England. The Method of making this, is to mix the raw express’d Juice of the Potatoes with a certain Quantity of Water; this in a seasoned Vessel will soon ferment, and in about four and twenty Hours be ready for Use; it tastes cool and sharp, and it is generally esteem’d a healthy Liquor. The Juice likewise of Potatoes, if fermented, will, by Distillation, yield good Spirit. The Vine producing each Sort is long, and trailing close to the Earth, taking Roots with its numerous Joints in wet Weather; these burrowing into the Ground bear a great Number of Potatoes: Tho’ the Leaves upon these different Vines vary somewhat in Shape, yet in general they are all scollop’d, and bear bell-fashion’d monopetalous Flowers, whitish without, and of a deep Purple within, each Flower being slightly segmented about the Edges. These are succeeded by small capsular Seed vessels, inclosing several blackish small Seeds.” [p. 228]

During the 19th century distinctly regional approaches to the sweet potato emerged. In the east the plant grew vigorously as far north as middle New Jersey, so most of the vegetables consumed in New England had to be carted in from regions more southerly. Because of a penchant for boiling the roots in their preparation for the table, northerners favored “dry” roots with a starchy quality: The Nansemond potato[5] (developed in Virginia and named after region of the eastern shore) served this taste and longed reigned as the favorite boiling potato of Yankee cooks. Southern cooks preferred baking their sweet potatoes and sought roots with moister flesh that would become fork tender after roasting in the fire or worked in an oven. The Southern Queen[6] potato, a shorter, rounder tuber than the Nansemond, became the tuber of choice, followed by a variety of yellow-fleshed ‘yams.” The Southern Queen’s qualities shone most brightly when double baked-put in the oven with skins on until soft, then removed, peeled, and baked another half an hour. “This way of baking twice, makes them more candied.”[7] During the mid-1880s, when southern women became conservators of regional memory, cookbooks began to appear tracing state and local traditions. Mary Stuart Smith in her Virginia Cookery Book surveyed the baking and boiling schools of preparation and asserted the local preference.

1. J. Lowell, “The Carolina Potato, or Sweet Potato,” New England Farmer 1, 47 (June 21, 1823), p. 372.
2. Jennifer A. Woolfe, Sweet Potato (Cambridge, & New York: Cambridge University Press, 1992), p. 42.
3. H.G. S., “Han. 29, 1831: For the Gennese Farmer,” Gennese Farmer 1, 6 (February 13, 1831.
4. “Sweet Potatoes,” Gennese Farmer 1, 14 (April 9, 1831), p. 109.
5. Also known as the “Jersey Potato” when grown in New Jersey.
6. Also widely known as the “Haymon Sweet Potato.”
7. Sarah Rutledge, The Carolina Housewife (Columbia: University of South Carolina Press, 1979 facsimile of the 1847 edition), p. 96.