Believe it or not, there are over 1,000 known types of sweet potatoes in the world and that’s not even counting the different types of yams – with which the sweet potato is often confused, but which is, in reality, a completely different plant. There are over 100 varieties grown in the United States alone, and the US doesn’t even rank as one of the top 10 producers.
Despite its name, the sweet potato is only a very distant relative of the potato and doesn’t even belong to the same family of plants. Botanically, the sweet potato plant is a member of the Ipomoea genus in the Convolvulaceae family of flowering vines and is more closely related to the Morning Glory (in which family it resides) than to either the potato or the yam.
The sweet potato itself is the tuberous root of the sweet potato vine and is consumed as a root vegetable. While the leaves and flowers are also edible (and are used in some Asian and African dishes), they are usually discarded in most parts of the West. The vine itself cannot be eaten.
Most cultivars of sweet potatoes can only be commercially grown in warmer temperate and tropical climates, as the plant is particularly susceptible to frost, although some hardier strains will grow in colder areas and have done so for centuries. A number of newer strains suited for colder environments have been developed in the last several decades.
The sweet potato most likely originated in South or Central America, and the first known cultivation and use of the vegetable date back to about 3,000 BC around the Yucatan Peninsula in what is now Southern Mexico. It made its way through Asia and Europe with the Spanish and Portuguese explorers throughout the middle and late 16th century and quickly became an important crop in both China and Japan. It was later brought to Central Africa (probably by Christian missionaries) and quickly became a widely cultivated crop there.
Far less popular in the United States and Western Europe than in many other parts of the world, just over 100 million tons of sweet potatoes are commercially cultivated worldwide today, with China accounting for close to 70% of that production. Nigeria, Tanzania, Indonesia, Uganda, and Ethiopia are other major world producers. In the United States (which produces about 1.5 million tons per year and ranks 9th in worldwide production) sweet potatoes are mostly cultivated in North Carolina, California, Texas, Mississippi and Louisiana.
Sweet potatoes come in a number of different colors, although reddish-orange is the most common in the West. While they are most often cooked in some way before being eaten, they can be (and in some cultures often are) consumed raw, although they will be harder to digest. Sweet potatoes are an excellent source of dietary fiber, vitamins A, B6, and C, as well as manganese and potassium.
Although sweet potatoes are most frequently consumed during holidays (or in pies and other baked goods) in North America, they very popular in US Southern cuisine, and are considered a staple food in some parts of Asia, Africa, and South America. As with so many other fruits and vegetables, horticulturists and scientists are continuing to work on developing new and stronger cultivars of sweet potatoes.
So what are some of the most popular types of sweet potatoes today?
Developed by scientists at Louisiana State University’s Agricultural Experiment Station and released in 1987, the Beauregard certainly isn’t the oldest type of sweet potato out there, but it is one of the most widely cultivated today. It is also one of the types you will most often find in the produce section of your local grocery store or farmer’s market.
Specifically bred to be resistant to most of the common diseases that attack root vegetables as well as white grubs (common insect larvae to which the sweet potato is particularly susceptible) the Beauregard sweet potato plant resists cold slightly better than many of its kin, although it still needs a relatively warm winter to thrive. The plant is particularly high-yielding and produces sweet potatoes with a relatively consistent shape and size, which makes them a favorite with farmers and consumers alike.
The Beauregard is a mid-size, early harvest, elongated sweet potato with reddish-orange skin and a fairly dark orange flesh. They have a sweet, buttery flavor – although not as sweet as some of the older varieties from which the plant was bred – and a firm texture. A quite durable vegetable, the Beauregard stores better than many other types of sweet potatoes (it will often remain good for up to a month) and is also highly resistant to cracking. This sweet potato is usually best used as a standalone complementary vegetable either whole or mashed or in casseroles and savory dishes.
An even more recent cultivar than the Beauregard – and catching up quickly to it in commercial popularity in the past decade – the Covington sweet potato was developed at North Carolina State University by Dr. Henry Covington (after whom it was named) and released to the market in 2006. A very disease resistant, durable and uniformly shaped sweet potato, the Covington currently accounts for 85 to 90 percent of all sweet potato production in the state of North Carolina (the largest sweet potato-producing state in the US), and is quickly making its way across Texas and California, as well as to Mexico, Western Europe and Asia.
The Covington is early to mid-season, small to medium size elongated sweet potato with smooth rose-colored skin and vibrantly bright orange flesh that retains its color after being cooked. The flesh is dense and quite firm, moist, and has a creamy sweet, slightly malty flavor when cooked or boiled. They are a favorite of many cooks for use in casseroles, serving as a standalone side dish (mashed or baked) and are sometimes shredded raw and used in salads. Very popular in restaurants due in large part to their uniformity of shape and texture, Covington sweet potatoes will usually last for a month or longer after they are harvested. They are not particularly well suited to candied dishes.
Often mistakenly labeled as a yam, the Jewel is another widely commercially grown cultivar of sweet potato, and is very popular throughout the United States, Canada and Western Europe. Another, earlier cultivar developed by researchers at North Carolina State University in conjunction with the North Carolina Department of Agriculture in the 1960s and released to the market in 1970, the Jewel is often referred to as the “Queen of sweet potatoes” and is mostly cultivated in its home state of North Carolina, Texas and California, as well as other parts of the world.
Considered by many chefs to be among the most versatile varieties, the Jewel is a medium size, oval, mid-season harvest sweet potato with a copper red color skin and a light orange, very moist flesh with a quite sweet, nutty and earthy flavor. Occasionally used raw to add color to salads, Jewel sweet potatoes stand up to both boiling and baking well, and are used as a vegetable accompaniment to a number of sweet and savory dishes, particularly in Southern cuisines. They are also sometimes used in soups, as pie filling, or cut into strips to make sweet potato fries. Due to their relatively high sugar content they will not keep as well as some other types of sweet potatoes, and will usually need to be used within about two weeks.
Still widely available in the United States and Canada, the Centennial been supplanted in recent years by the Beauregard and Covington as far as commercial production is concerned, but it remains a popular sweet potato with commercial growers and home gardeners alike, particularly in colder climates. Developed at Louisiana State University through the late 1950s and introduced to the market in 1960, the Centennial was the ‘go to’ sweet potato for many cooks and growers throughout the 1960s and early 70s, before it was overtaken by the more popular Jewel.
The Centennial is a fairly fast-growing sweet potato plant, which makes it quite popularly with gardeners and farmers that have a shorter growing season; the sweet potato itself will normally reach maturity in between 90 and 100 days. The Centennial is a medium to large, elongated sweet potato with a copper red skin and a carrot-orange flesh that is finely-grained, moist, has an earthy sweet flavor. Nicknamed the ‘baby baker’, they are commonly served in place of a standard baked potato, as well as widely used for sweet potato fries and other cooking applications.
The Garnet is another sweet potato that is often mistaken for a yam, and is actually sold as a type of red yam in grocery stores throughout the United States and Canada. Particularly popular during the holiday season, Garnet sweet potatoes first appeared in the 1950s. Not a particularly sturdy sweet potato plant, the Garnet grows best in the deep Southern United States, Texas, and California.
Named for its maroon skin which is similar to the gem stone of the same name, the Garnet is a large, elongated sweet potato that will often grow up to a foot in length. Its flesh is golden orange, moist and firm and has a very sweet, earthy flavor. Garnet sweet potatoes are almost exclusively used in cooked and baked applications, in large part because of their high moisture content, and are popular as a mashed or baked side dish, and often used to make fries and pie fillings. They are also often the main ingredient in candied recipes. A relatively durable and good storing vegetable, the Garnet will usually last between 3 and 4 weeks.
The Nancy Hall is an older or ‘heirloom’ type of sweet potato that, in the time between the First and Second World Wars, was among the most popular sweet potatoes in North America. First discovered by accident in the mid-1890s in Tennessee (one legend has it that it was the result of an accidental crossing of potato and flower seeds by a woman named, not surprisingly, Nancy Hall), it was once so popular that it actually had a parade named in its honor. Widely replaced in recent decades by hardier more recent cultivars, the Nancy Hall has seen something of a rediscovery and resurgence in the last ten years and is currently becoming increasingly popular with home growers and some smaller farmers.
Still considered a mostly ‘Southern’ sweet potato as it has a very low tolerance for cold weather, the Nancy Hall is a small to medium size, mid-season variety with a golden yellow skin and a creamy white, juicy and sweet flesh. Sometimes baked and used in place of a regular potato as a vegetable, the Nancy Hall in most often used in sweet and savory recipes, and stands up exceptionally well to candying. This sweet potato is not particularly durable, and will usually need to be used within a week or two of harvest.
Quite possibly the original sweet potato encountered by explorers in South and Central America back in the 16th century, the Boniato is one of the most widely cultivated sweet potatoes in China and other parts of Asia, where it is considered to be a staple food. It is also widely grown throughout Central America, Africa and the Caribbean.
Also called the Batata, Cuban and Caribbean sweet potato, the Boniato is fairly large and elongated, with a bumpy brown, purple, and rose splotched skin and a creamy white flesh with a nutty, starchy flavor that is only slightly sweet. Normally used in the same ways that a regular potato is used, it is a major part of many regional Asian and Central American cuisines, and is far more popular in other part of the world than it is in North America. It is only commercial cultivated in the United States in Florida, mostly due to that state’s large Cuban population.
The Vardaman sweet potato plant is a compact, relatively short vine that is quite popular with home growers with limited gardening space throughout the United States because of its small size and high yield. Developed by the Mississippi Agricultural Extension Service and released in 1981, it is named after Vardaman, Mississippi – the self proclaimed ‘Sweet Potato Capital’. A sturdy plant that tolerates cold temperatures very well, the Vardaman is an elongated, medium size sweet potato with golden yellow skin that darkens after harvest and a deep orange, sweet moist flesh. Good for all types of cooked applications, Vardaman sweet potatoes will not last as long as some other varieties, and should usually be used within two weeks of harvest.
Developed at Louisiana State University and released in 1992, the Hernandez is another plant bred to survive in both warm and colder climates, and has become popular with home gardeners in the last decade. A high yield mid-season harvest plant, the Hernandez produces a fairly large elongated sweet potato with a dark red skin and a fairly bright orange flesh. The flavor is very sweet, and the flesh tends to be quite moist and less ‘stringy’ than many other varieties. It holds up to baking exceptionally well.
A true heirloom variety of sweet potato, the Jersey Yellow has probably been around for over 200 years, and has remained a favorite of small farmers and home growers to the present day. A fairly sturdy plant that does best in warmer areas, the Jersey Yellow is a medium size, mid season harvest sweet potato with a usually golden yellow skin that will fade to a light tan during storage and a white to yellow flesh sometimes shot through with pink. The flavor is quite sweet, and the flesh is very firm and fibrous and remains dry after cooking, allowing the sweet potato to retain its shape. Most often baked and served as a side dish, it is also sometimes used to make fries, stews and casseroles.
Discovered and first cultivated in the late 1990s in Vardaman, Mississippi, the O’Henry is a natural white-flesh genetic mutation of the orange-flesh Beauregard sweet potato. Like its more popular progenitor, the O’Henry is a quite durable plant that will grow well in colder climates and is very resistant to pests and disease. The sweet potato is an early season, slightly elongated vegetable with a light tan skin. The flesh, as stated, is pale yellow to white, dense, firm and moist with a sweet flavor that has hints of honey and nuts. Most often used in sweet and savory dishes or as a standalone vegetable, the O’Henry is also popular as a pie filling, and stands up to candying well.
A relatively new and quite unique cultivar, the Stokes Purple is a patented sweet potato variety first cultivated in Stokes County, North Carolina in 2003 and released to the market in 2006. Still grown almost exclusively in its home state and in California, the Stokes Purple has a semi-smooth brownish-rust skin and a vibrant purple flesh shot through with white and violet. A large, elongated sweet potato, it has a dense texture and is less sweet than many other varieties, and contains one of the highest levels of antioxidants of all sweet potato varieties. Along with being suitable for most sweet potato cooking and baking applications, it is also frequently used as a garnish or thinly sliced to bring extra color to salads. In the last few years, scientists have been experimenting with the Stokes Purple as a possible natural food coloring source.
Native (not surprisingly) to Japan where they have been grown since the mid-18th century, Japanese sweet potatoes are widely commercially cultivated there as well as in China, India, Vietnam and Indonesia. The products that you will most often find sold in US markets as ‘Japanese’ or ‘Oriental’ sweet potatoes, however, are actually usually fairly recent cultivars of plants originally from Japan developed in the United States over the last 30 or forty years. Mostly grown in Louisiana, North Carolina, Alabama, Georgia and Mississippi, these ‘Japanese’ sweet potatoes are usually medium to large size vegetables, oblong as opposed to elongated, and will have skins that range from pink to red to light purple. The flesh will usually be white to pale yellow, have a dry somewhat coarse texture, and a slightly sweet, nutty flavor. Japanese sweet potatoes are good as a standalone vegetable, can be used in soups, and are particularly well suited to curry and stir fry dishes.