Get to know sweet potatoes and cranberries a little better.

Next Thursday, many Americans will partake of a Thanksgiving dinner, stuffing themselves with an assortment of foods. The meals may include two plants: cranberries and sweet potatoes.

Sweet potatoes are members of the morning glory family, the only plant of much economic importance in that family.

Sweet potatoes aren’t really potatoes — that Irish tuber belongs in the nightshade family with tomatoes, eggplants and peppers. However, sweet potatoes are sweet.

Nor are sweet potatoes the same thing as yams — though many will take the Southern U.S. stance, particularly in Mississippi and Louisiana, that a sweet potato that’s moist and extremely sweet is a yam. Thankfully, Southerners call it sweet potato pie instead of yam pie.

Yams are tropical vines that produce a swollen stem above ground that is white and extremely large, resembling a large, football-size sausage. The yam is extremely starchy and a main part of the diet of some cultures in Africa, Asia and Latin America. Occasionally, you’ll find a true yam in the grocery store.

True sweet potatoes are native to South America and have been cultivated for many centuries. We only eat the tuberous root, but the leaves and stems are also edible. Fortunately or unfortunately, you can’t find the leaves and stems unless you grow your own.

The ornamental sweet potato vines with the dark-red and chartreuse foliage will produce tuberous roots, but usually not in sufficient size to warrant adding brown sugar, maple syrup, molasses and/or marshmallows. Most are usually as thick as a big magic marker. They’re better scrubbed and roasted as fries.

Keep sweet potatoes somewhere on the cold side with high humidity. A refrigerator may provide cold, but frost-free ones take out the humidity, so the sweet potato root will probably start shriveling fast. A cold crawl space with temperatures in the mid- to low-50s is probably best. Freezing them is not practical, as the sweet potato turns mushy.

They will keep, however, for several months under the sink or even on the counter without much loss in quality.

Cranberries are found throughout the northern hemisphere, but Wisconsin produces more than 50 percent of the berries.

These bog berries, also called Fenberries and Mossberries, belong to the same genus as blueberries, and are closely related to azaleas and rhododendrons.

For years, cranberries were associated with Thanksgiving and Christmas. That all changed about 40 to 50 years ago, when the Ocean Spray cooperative took off. Today, roughly 65 percent of all cranberries go through the Ocean Spray cooperatives.

Cranberries grow in bogs, but not in water. The small cranberry evergreen shrub is planted in sandy soil and irrigated throughout the growing season, but it’s definitely not flooded. The bogs are filled with water only during the harvest period, covering the plants with 6 inches of water. As you can see in the commercials, we’re only talking about calf- to knee-high water.

The ripe berries will float to the surface where harvesting machines and skimmers gather them.

For the cook, floating the berries in water will tell you which ones are good and which aren’t. If the cranberry sinks, it’s better off in the compost pile or down the garbage disposal.

These days, cranberry cooperatives market the berries year-round. You can find cranberry sauce and jelly on grocery shelves 365 days a year. Craisins, dried cranberries, have almost surpassed raisins as a snack food.

And cranberries, like blueberries, have benefited from lots of health studies over the past 20 years that show the fruit is high in antioxidants.

Unlike sweet potatoes, you can freeze cranberries whole. Some people just throw the bag in the refrigerator. Others put the berries on a sheet to freeze first, and then put them in freezer bags. The berries will freeze indefinitely, but like most frozen fruit, should be eaten within a year for best flavor.

You can keep the berries in the refrigerator produce drawer for several months, though it’s a good idea to wash and remove the soft ones regularly.

Cranberries also are noted to have a soothing, relaxing effect, especially when combined with vodka, triple-sec and a little lime juice.

For more gardening information, go to www.extension.uiuc.edu/mg.