In the spring, local greenhouses sell sweet potato slips, the sprouts from which sweet potato tubers grow. You’ll probably have to ask a clerk to direct you to them, as they are frequently stashed off to the side.

Sweet potatoes are a staple of the Southern garden, but in this climate, where they can take as long as six months to mature, depending on the variety, they are the exception. In the Midwest, we also tend to ignore the sweet potato until the Thanksgiving season, when it returns, year after year, to its obligatory place on the table.

Over the years I have had several readers tell me that they grow sweet potatoes for their blooms as well as for their meat. A relative of the morning glory, the sweet potato is really not a potato at all, but the root of a gorgeous vining plant.

It turns out that the link between the sweet potato and Thanksgiving is more than a coincidence. For one thing, the sweet potato is harvested in late summer or early fall, so it is a seasonal vegetable. In addition, the sweet potato, a food native to the so-called New World, is deeply embedded in the lore of the early American colonies, on which the traditional Thanksgiving menu was fashioned.

Vegetable connoisseur Bert Greene has written that the sweet potato was a primary source of sustenance to settlers at Jamestown.

Greene also suggests that the sweet potato was taken by early explorers, including Columbus, from South America to Spain, and that the Spanish only reluctantly shared this treasure with other Europeans. The English obtained the sweet potato through the dowry of Catherine of Aragon. Her husband, Henry VIII, grew so fond of sweet potatoes that he consumed them by the dozen and offered prizes to any English gardener who could make the sweet potato grow in the cool English climate.

Ironically, the sweet potato, which already was a native of the Americas, was reintroduced by the colonial settlers, who brought them from Europe. Greene notes that sweet potatoes also were a logical food for slaves because of their similarity to the yam, which flourished in Africa.

Hardly a southern cookbook is published without a fair sampling of sweet potato recipes. Many of them, especially those for sweet potato souffle and mashed sweet potatoes, call for a tablespoon or two of bourbon or cognac.

When I was a child my mother initially enticed me to eat sweet potatoes by baking them up in a casserole topped with marshmallows, which melted and browned to form a tooth-rotting sugar crust. Later, the sugar overdose disappeared, and sweet potatoes most often appeared on the table baked into a seasonal casserole with apples and sometimes raisins.

This version, it turns out, is something of an American classic. For example, a similar recipe appeared in “The Historical Cookbook of the American Negro,” which first appeared in 1958 and was republished in 2000. This recipe dates to 1922.

While I might use half as much brown sugar and butter, this recipe still holds up over time.

As with many older recipes, however, the authors of this recipe assumed that readers would take certain information for granted. The sliced apples should be placed in a bowl before the citrus juice is poured over them to keep them from browning. Second, for cooked sweet potatoes, boil them with skins on to retain the nutrients. When they are slightly tender, removed them from the water and let cool. Peel them before assembling this recipe. And finally, the butter should be softened.

Sweet potatoes with apples

6 cooked sweet potatoes

3 apples

1/2 cup butter

1/2 cup brown sugar

1/2 teaspoon nutmeg

1/2 cup orange juice or lemon juice

Peel and slice apples. Add the orange juice. Butter a casserole and alternate sliced sweet potatoes and apples until the dish is full. Mix sugar, butter and nutmeg together. Spread over apples and potatoes. Bake until brown. Maple sugar may be substituted for brown sugar. Baking temperature 400 degrees. Baking time: 30 to 45 minutes.