Sweet Potatoes and Yams
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40 free Sweet Potatoes and Yams trivia questions with answers — trivia quiz, new questions added Oct 2026.
Sweet potatoes and yams share a shelf in the shop and a spot on the holiday table, yet they are not the same plant, and not even close relatives. Most people have never knowingly tasted a true yam. That mix-up is where this quiz begins. The questions cover how to tell the two apart, where each crop comes from, how they travelled the globe, and the dishes cooks have made from them on every continent, from street snacks to festival feasts. A few dig into the botany and the surprising science hiding inside these humble crops. It is pitched for curious cooks, gardeners and anyone settling a dinner-table argument about what is really in the casserole. Every answer comes with a short explanation, so you will leave knowing more than you did.
30 of 40 questions with answers and explanations. Play the quiz
Q 01A compound made from wild Mexican yams by chemist Russell Marker paved the way for which landmark medicine?
The contraceptive pill
The contraceptive pill grew out of the cheap progesterone Marker learned to make from yam roots, founding a steroid industry in Mexico. He had earlier invented the octane rating for fuel.
Q 02Cultivated sweet potatoes are a natural GMO, carrying genes picked up long ago from which kind of organism?
Bacteria
Bacteria of the Agrobacterium group inserted their DNA into an ancestor of the crop, and the genes still work today. That makes sweet potato the first known naturally transgenic food crop.
Q 03Sweet potatoes are only distant cousins of ordinary potatoes and belong to which flowering plant family?
Morning glory
Morning glory is the family, and sweet potato is its only major food crop. The ordinary potato sits with tomatoes among the nightshades, and true yams are more distant still.
Q 04Candied yams, the sweet potato side dish of American Thanksgiving, are often baked under which topping?
Marshmallows
Marshmallows melt over a dish that contains no yams at all. The name is a misnomer, because true yams became rare in American kitchens after colonial times.
Q 05Which West African country grows about two-thirds of all the true yams harvested in the world?
Nigeria
Nigeria harvested 67% of the world's yams in 2020. The crop is so prized in the region that many communities hold a festival before anyone may eat the new harvest.
Q 06The word yam reached English through Portuguese or Spanish from West African words with which everyday meaning?
To eat
To eat is the root sense, from words such as the Wolof for food. Enslaved Africans in America are said to have given the name to the sweet potatoes that reminded them of home.
Q 07Long before Europeans reached the Americas, sweet potatoes were already grown across which Pacific region?
Polynesia
Polynesia had the crop at least 600 years ago, as dated remains in the Cook Islands show. The leading idea is that island voyagers reached South America and sailed home with cuttings.
Q 08The vivid purple yam behind Filipino jams, cakes and ice cream is best known by which Tagalog name?
Ube
Ube is a true yam, and nearly all its varieties are sterile, so it reached each Pacific island only in human hands. That makes it a living tracer of ancient voyages.
Q 09Sweet potatoes once supplied most of the calories in the traditional diet of which Japanese islands?
Okinawa
Okinawa got about 69% of its calories from sweet potatoes around 1950, with rice a distant second. The crop had arrived in the early 1600s, when the islands were the Ryukyu Kingdom.
Q 10In New Zealand, sweet potatoes are sold under which name, taken from the Māori language?
Kūmara
Kūmara came with the first Māori settlers, who grew finger-sized yellow varieties. Larger kinds brought by American whalers in the early 1800s soon took over.
Q 11The English word potato descends from batata, the sweet potato's name in which indigenous American language?
Taíno
Taíno speakers of the Caribbean gave the Spanish the word batata. Spaniards are thought to have blended it with papa, an Andean word for the ordinary potato, to make patata.
Q 12George Washington Carver wrote farm bulletins on sweet potatoes and peanuts while teaching at which institute?
Tuskegee
Tuskegee was where Carver logged scores of sweet potato products, among them 73 dyes, 14 candies and 5 library pastes. He urged poor farmers to grow the crop to feed themselves.
Q 13Which state, the top sweet potato grower in the United States, made it the official state vegetable in 1995?
North Carolina
Q 21True yams are monocots, which makes them closer relatives of which plants than of sweet potatoes?
Lilies and grasses
Lilies and grasses are monocots, sprouting with a single seed leaf, and yams belong with them. Sweet potatoes are dicots, so the two look-alike crops sit on far-apart branches of plant life.
Q 22At the market, a true yam can be told from a sweet potato by which kind of skin?
Rough and hard to peel
Rough and hard to peel is the giveaway, though cooking softens it. Inside, the flesh runs from white or yellow to purple or pink, and a tuber can reach 1.5 metres down into the soil.
Q 23Most yams must be cooked to be safe, but Japan's nagaimo yam is commonly served in which way?
North Carolina has ranked first among sweet potato states since 1971. Fourth-graders in the town of Wilson petitioned lawmakers for the honour after a visit from their local representative.
Q 14Sweet potato pie, a holiday dessert of the American South, stands in for a pie filled with what?
Pumpkin
Pumpkin is the holiday pie elsewhere in the country. Enslaved Africans likely used sweet potato as a stand-in for the yam of their homeland, and European pie-making did the rest.
Q 15The first Europeans to taste sweet potatoes, on Hispaniola, belonged to an expedition led by which explorer?
Christopher Columbus
Christopher Columbus's expedition met the crop in 1492, and it crossed the Atlantic soon after. By 1604 it was turning up in an English country-house recipe book.
Q 16Ceviche is traditionally served with boiled sweet potato, called camote, in which South American country?
Peru
Peru pairs its citrus-marinated fish with sweet potato and has prized the root for millennia. Potters of the ancient Moche culture there shaped vessels like sweet potatoes.
Q 17Which Japanese spirit, usually made from rice or barley, is also famously distilled from sweet potatoes?
Shōchū
Shōchū distilled just once keeps the strong taste and aroma of its sweet potatoes. A boom in the drink in the early 2000s caused a serious shortage of the roots in Japan.
Q 18Dangmyeon, the chewy glass noodles made from sweet potato starch, are the heart of which stir-fried dish?
Japchae
Japchae began as a noodle-free vegetable dish that so pleased a 17th-century king he promoted its inventor to high office. The sweet potato noodles joined only in the 20th century.
Q 19Sweet potatoes are usually grown not from seed but from sprouts taken off a stored root, known as what?
Slips
Slips are shoots that sprout from a root kept in storage, each one planted out to become a new vine. True seeds are used only by breeders.
Q 20Orange-fleshed sweet potatoes are promoted across Africa to fight a widespread deficiency of which nutrient?
Vitamin A
Vitamin A is made in the body from the beta-carotene that colours the flesh. Breeding and spreading these roots earned their champions the World Food Prize in 2016.
Raw and grated
Raw and grated nagaimo becomes tororo, a sticky purée poured over rice, noodles or tuna. Cooks soak the tuber in vinegar water first so its needle-like crystals do not irritate the skin.
Q 24The air potato, a yam vine introduced in 1905, has since become an invasive pest across much of which US state?
Florida
Florida cannot shake it, because new vines sprout from the potato-sized bulbils that grow along the vine, even after cutting or burning. Wild forms growing there can be poisonous.
Q 25The New Yam Festival, called Iri ji or Iwa ji, is the great harvest celebration of which West African people?
Igbo
Igbo custom holds that nobody touches the fresh crop until the feast, when yams are first offered to gods and ancestors. One scholar called them the most enthusiastic yam growers in the world.
Q 26In Malaysia and Singapore, the word yam on a menu usually means which other starchy crop?
Taro
Taro takes the name there, one of several unrelated plants called yams. Others include the yam daisy of Australia and the elephant foot yam of Asia.
Q 27In New Zealand, the small pink tubers sold as yams are actually which Andean crop, a kind of wood sorrel?
Oca
Oca became a popular table vegetable in New Zealand after arriving in the 19th century. It is no relation of the true yams, which sit in a separate plant family.
Q 28The botanical genus of the true yams was named in honour of which ancient Greek physician and botanist?
Dioscorides
Dioscorides gave his name to the genus Dioscorea, chosen by the monk and plant collector Charles Plumier. It holds hundreds of species, a few grown for food and others toxic.
Q 29Dried yam ground into flour and stirred into boiling water makes which dark Yoruba dish, eaten with soups?
Amala
Amala turns dark brown because the yam slices darken as they dry in the sun before milling. The flour itself is called elubo.
Q 30On which islands of Papua New Guinea are yams valued as a currency that stands for wealth and power?
The Trobriands
In the Trobriands, custom has a man give his yam harvest to his sister's household, so that her children are fed by their mother's line rather than their father's.