Sweet potato

The sweet potato or sweetpotato (Ipomoea batatas) is a dicotyledonous plant in the morning glory family, Convolvulaceae. People grow it for its big, starchy, sweet-tasting tuberous roots, which they eat as a root vegetable. These roots are a staple food in many parts of the world.

Sweet potatoes grew naturally in the tropical parts of South America, especially in modern-day Ecuador. The sweet potato belongs to the genus Ipomoea, which also includes beautiful garden flowers called morning glories. In North America, sweet potatoes are sometimes called yams, but they are not related to real yams, which come from a different plant family.

Description

The sweet potato is a leafy plant with vines that grow along the ground. Its leaves are triangle-shaped or lobed and can be green or sometimes purple. The plant makes pretty flowers, usually in shades of purple or lavender.

The part we eat is the tuberous root underneath the soil. It has smooth skin that can be yellow, orange, red, brown, purple, or beige. Inside, the flesh can be white, red, pink, violet, yellow, orange, or purple. Some types are sweeter than others.

Taxonomy

The sweet potato originates in South America, in what is now Ecuador. People started growing sweet potatoes in Central or South America at least 5,000 years ago. They likely spread from places like the Yucatán Peninsula in Mexico to the Caribbean and South America by the year 2500 BCE.

Sweet potatoes are closely related to a wild plant called I. trifida. Over time, sweet potatoes changed and adapted, becoming a special kind of food crop.

Cultivation

See also: Sweet potato storage

Dispersal history

Long ago, people in Polynesia grew sweet potatoes. They spread them by cutting pieces of the vine, not using seeds. Scientists found that sweet potatoes were in the Cook Islands between 1210 and 1400 CE. Many think Polynesians brought sweet potatoes from South America to Polynesia, spreading them to places like Easter Island, Hawaii, and New Zealand. Words for sweet potatoes in Polynesian and South American languages are similar, showing that people traveled between these places long ago.

Sweet potatoes reached Europe after European explorers found the Americas. They were first written about in England in 1604. The sweet potato came to the Philippines when Spain ruled the area. It was later brought to China around 1594 after a big crop failure. Sweet potatoes also became important in Japan in the early 1600s, helping to prevent hunger when rice crops failed. They were introduced to Korea in 1764 but did not succeed there.

Names

See also: List of sweet potato cultivars

Though sometimes called a "yam" in North America, the sweet potato is not the same as a yam. Yams are a different plant from a different plant family. The word "sweet potato" comes from the Taíno people of the Caribbean. Europeans mixed their word with another language's word for potato. In many places, sweet potatoes have different names. For example, in some South American countries they are called "batata," and in others "camote."

Habitat

Sweet potatoes grow best in warm places with plenty of sunshine and warm nights. They need about 750 to 1,000 mm of rain each year. These plants do not like cold frost and grow best around 24 °C (75 °F). They can be grown in many types of soil but do best in well-drained soil that is not too acidic or too alkaline. Sweet potatoes are usually grown from pieces of the vine rather than seeds. They are not troubled by many pests and can grow in poor soils with little fertilizer.

Depending on the type, sweet potatoes can be ready to harvest in two to nine months. In warm places, they can be grown as a summer crop. Sweet potatoes do not need many chemicals to grow and can be raised in many farming conditions. In the tropics, they can stay in the ground and be picked as needed, but in colder places they are usually harvested before frost.

Sweet potatoes are grown in tropical and warm temperate areas around the world where there is enough water. In the Caribbean, a type called "boniato" is grown, which has cream-colored flesh and is less sweet than other sweet potatoes.

Production

In 2020, the world produced about 89 million tonnes of sweet potatoes, with China producing more than half of that amount. Other big producers include Malawi, Tanzania, and Nigeria. Sweet potatoes are an important food crop, especially in developing countries. Scientists are working on creating types that can survive with less water to help with climate change.

Diseases

Main article: List of sweet potato diseases

Sweet potatoes can get sick with viruses and other plant diseases, which can make them look unhealthy and reduce their yield.

Uses

Nutrition

Cooked sweet potato is mostly water and contains carbohydrates, protein, and a little fat. It gives you vitamin A, vitamin C, manganese, and vitamin B6. It also has some B vitamins and potassium. Sweet potato leaves can be eaten like spinach.

Comparison to other food staples

The table below shows how sweet potato compares to other staple foods. Sweet potato has less energy and protein than grains but has more nutrients.

Sweet potatoes grow well and need less land than many other foods.

Culinary

The roots of the sweet potato are most often eaten. They are usually cooked before eating. The leaves and young vines can also be eaten as a green vegetable.

In Africa, sweet potatoes are used in many dishes. In Kenya, they are used in new recipes. In Egypt, they are a common street food.

In Asia, roasted sweet potatoes are popular. In China and Korea, they are often eaten in winter. In Japan, they are called yaki-imo. Sweet potato soup is eaten in winter in many Asian countries. In the Philippines, sweet potatoes are an important crop.

In the United States, sweet potatoes are used in dishes like candied sweet potatoes and sweet potato casserole, especially during Thanksgiving. Fried sweet potatoes are also popular.

In Oceania, sweet potatoes, called kūmara, are cooked in earth ovens. In New Zealand, they are often part of meals.

In Europe, sweet potatoes are used in many dishes. In Spain, they are called boniato.

In South America, sweet potatoes are used in dishes like ceviche in Peru.

Globally, sweet potatoes are used in modern sushi with sweet potato rolls.

Molecular gastronomy

Freezing a sweet potato, then baking it at different temperatures, brings out its sweetness.

Ceramics

Ceramics shaped like sweet potatoes are found in the Moche culture.

Dyes

In South America, red sweet potato juice mixed with lime juice makes a dye for cloth. Purple sweet potato color is used as a natural food coloring.

Aquariums

Cuttings of sweet potato vine can grow roots in water, making them good for home aquariums.

Ornamentals

Ornamental sweet potatoes are popular plants for gardens. They grow quickly and come in many colors. Some varieties flower more than others. The leaves can be eaten, but the tubers do not taste good.