Tomato
In 1893, the United States Supreme Court had to decide what a tomato was. On the 10th of May that year, in a case called Nix v. Hedden, the justices ruled that for the purposes of the Tariff of 1883, the tomato counted as a vegetable. Their reasoning leaned on the kitchen rather than the laboratory. Tomatoes are served with dinner, not with dessert. Botanically, the court was wrong. The tomato, Solanum lycopersicum, is a fruit, and more precisely a berry, grown from the ovary and seeds of a flowering plant. How did a plant from western South America end up arguing its identity before the highest court in America? Why was it once shunned as poisonous, dubbed a globe of the devil, and grown only for its beauty? And how did a fruit that humans deliberately made less sweet become one of the most widely used ingredients on the planet?
Galen, the ancient physician, used the name lycopersicum, meaning wolf peach, for a plant that has never been identified. Centuries later, in the 16th century, Luigi Anguillara guessed that Galen's wolf peach might be the tomato. The identification was impossible, yet lycopersicum entered scientific use as a name for the fruit anyway. The word tomato itself traveled a cleaner path. It comes from the Spanish tomate, which comes from the Nahuatl word tomatl.
The tomato belongs to the genus Solanum, part of the nightshade family, the Solanaceae. Its relatives are a strange and often poisonous crowd. They include the mandrake, deadly nightshade, tobacco, the potato, and chili peppers. That family resemblance haunted the tomato for centuries, because people assumed a cousin of deadly nightshade must itself be dangerous.
In 1753, Linnaeus placed the tomato in the genus Solanum, naming it Solanum lycopersicum. In 1768, Philip Miller disagreed and moved it to its own genus as Lycopersicon esculentum. That name spread widely, even though it technically broke the plant naming rules, since Linnaeus's species name had priority. Because Lycopersicon esculentum had become so familiar, it was officially listed as a conserved name in 1983. Genetic evidence has since shown Linnaeus had it right all along, making Solanum lycopersicum the correct name. Two reasons once argued for keeping the genera apart. Tomato leaves are markedly different from any other Solanum, and many of the alkaloids common to other Solanum species are absent from the tomato. Yet hybrids of tomato and diploid potato can be created in the lab by somatic fusion, and they are partially fertile.
Genomic analysis predicts that the cherry tomato variety, var. cerasiforme, appeared around 78,000 years ago, while the cultivated tomato originated around 7,000 years ago, around 5,000 BCE. The likely wild ancestor is the red-fruited Solanum pimpinellifolium, native to western South America, where it was probably first domesticated. The domestication story is messier than a simple line of descent. Traits supposedly typical of domestication may have been reduced in the cherry tomato and then reselected in the cultivated tomato, a case of convergent evolution.
When Mesoamericans domesticated the tomato, they selected for less bitter fruit. That choice tracked the increased activity of an enzyme called 23DOX during ripening, which converts the bitter and slightly toxic alpha-tomatine into hydroxytomatine, and eventually into the non-bitter, non-toxic esculeoside A.
The poor taste of modern garden and commercial tomatoes came from a later human choice. In the mid-20th century, breeders found a mutant phenotype labeled u, so named because its fruits ripened uniformly. They cross-bred it widely to make tomatoes that ripen evenly red without the green ring around the stem. The cost was flavor. The u mutation produces defective chloroplasts with lower density in the developing fruit, reducing sugar in the ripe tomato by 10 to 15%. In the developing fruit of the normal U phenotype, 10 to 20% of the total carbon fixed can come from photosynthesis inside the fruit itself. Combining the advantages of both types in one commercial variety requires fine tuning, but may be feasible.
Hernán Cortés captured Tenochtitlan in 1521, opening the cultural and biological interchange called the Columbian exchange. Before that conquest, the Aztecs already raised several varieties, calling the red ones xitomatl. Bernardino de Sahagún described a great variety of tomatoes in the Aztec market at Tenochtitlán: large tomatoes, small tomatoes, leaf tomatoes, sweet tomatoes, large serpent tomatoes, and nipple-shaped tomatoes, in colors from the brightest red to the deepest yellow. He also recorded the Aztecs cooking sauces with tomatoes of different sizes and serving them in city markets.
The tomato reached Europe within a few years of the conquest, cultivated by the 1540s and thriving in Mediterranean climates. Its first appearance in European literature came in Pietro Andrea Mattioli's herbal of 1544. He thought a new kind of eggplant had arrived in Italy, describing fruit that was blood-red or golden when ripe, divided into segments, and eaten cooked with salt, black pepper, and oil. Ten years later, Mattioli named the fruits in print as pomi d'oro, golden apples.
In 1548, the house steward of Cosimo de' Medici, grand duke of Tuscany, wrote to the Medici private secretary that a basket of tomatoes sent from the Florentine estate at Torre del Gallo had arrived safely. For a long time, Italians grew tomatoes mainly as ornamentals. The Florentine aristocrat Giovanvettorio Soderini wrote that they were to be sought only for their beauty, kept in gardens and flower beds. Their habit of growing close to the ground suggested low status, and they were not as filling as other crops, so peasants did not adopt them as a staple. In Florence, the fruit served only as a tabletop decoration until the local cuisine absorbed it in the late 17th or early 18th century. The earliest known cookbook with tomato recipes was published in Naples in 1692, though its author had apparently taken those recipes from Spanish sources.
John Gerard, a barber-surgeon, was one of the earliest English cultivators of the tomato. His Herbal, published in 1597 and largely plagiarized from continental sources, gives one of the earliest English discussions of the fruit. Gerard knew tomatoes were eaten in Spain and Italy, yet he believed they were poisonous. His influence lingered. The tomato was considered unfit to eat for many years in Britain and its North American colonies.
By 1820, tomatoes were described as seen in great abundance in all the vegetable markets and used by all the best cooks. Even then, some gardens still grew them for the singularity of their appearance, and their use in cooking carried an exotic Italian or Jewish association. In Elizabeth Blackwell's A Curious Herbal, the tomato appears under the name Love Apple, eaten with oil and vinegar in Italy much as the British ate cucumbers. In 1963, an American newspaper explained the name Love Apple as a French misreading of the Italian pomo dei Mori, the Moors' apple, as pomme d'amour, apple of love.
In British North America, the earliest record of tomatoes being grown dates to 1710, when the herbalist William Salmon saw them in what is now South Carolina. Thomas Jefferson, who ate tomatoes in Paris, sent seeds back to America. Many Americans still thought the fruit poisonous and grew it as an ornamental. In 1897, W.H. Garrison recalled that in his youth tomatoes were called love-apples or wolf-apples and shunned as globes of the devil.
Alexander W. Livingston, who lived from 1821 to 1898, set out to grow tomatoes smooth in contour, uniform in size, and sweet in flavor. He eventually developed over seventeen varieties. His first breed, the Paragon, was introduced in 1870, and the Acme followed in 1875, said to be in the parentage of most cultivars for the next twenty-five years. The U.S. Department of Agriculture's 1937 yearbook declared that half of the major varieties resulted from the Livingstons' ability to evaluate and perpetuate superior material in the tomato.
Because the tomato needs heat and a long growing season, Sun Belt states became major producers, particularly Florida and California. In California, tomatoes are grown under irrigation for both the fresh market and for canning. The University of California, Davis maintains a gene bank of wild relatives and genetic stocks at its C.M. Rick Tomato Genetics Resource Center. Some California growers practice dry-farming, especially with Early Girl tomatoes, a method that pushes roots deep to find existing moisture.
The genome itself became a target. An international consortium from 10 countries began sequencing the tomato genome in 2004, and the complete genome for the cultivar Heinz 1706 was published on the 31st of May 2012. The first commercially available genetically modified food was a tomato, the Flavr Savr, engineered for a longer shelf life so it could ripen on the vine. It was not firmer than its parent, its yields were subpar, and it sold only until 1997.
In 2023, world production of tomatoes reached 192 million tonnes, led by China with 36% of the total, followed by India, Turkey, and the United States. China received the tomato in the 16th century, likely by way of the Philippines or Macau, and named it fānqié, foreign eggplant. After the Spanish colonization of the Americas, the fruit spread through their Caribbean colonies, then to the Philippines, then across Asia. It reached the Middle East through John Barker, the British consul in Aleppo from about 1799 to 1825.
The tomato's umami flavor made it central to cuisines worldwide. It anchors pizza and pasta sauces, Spanish gazpacho, and Catalan pa amb tomàquet. Across the Middle East it appears fresh in salads like the Arab, Israeli, Shirazi, and Turkish versions, and grilled with kebabs. Europeans carried it into Indian cooking, where it entered curries like the Kashmiri rogan josh, and the modern British curry tikka masala often comes in a tomato and cream sauce.
The fruit also became a thing to throw. In the town of Buñol, Spain, the festival of La Tomatina centers on an enormous tomato fight. On the 30th of August 2007, as many as 40,000 people gathered to hurl 115,000 kilograms of tomatoes at one another. Tomatoes are also thrown in public protests, a connotation the Dutch Socialist party embraced by adopting the tomato as its logo. The film and television review site Rotten Tomatoes carries the same association, though its founder credits a scene in the 1992 movie Leolo as the immediate source of the name. Some growers have managed feats of abundance rather than destruction. A massive tomato tree in the experimental greenhouses at the Walt Disney World Resort in Lake Buena Vista, Florida yielded more than 32,000 tomatoes, together weighing 522 kilograms.
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Common questions
Is a tomato a fruit or a vegetable according to the Supreme Court?
The U.S. Supreme Court ruled in Nix v. Hedden on the 10th of May 1893 that the tomato is a vegetable for the purposes of the Tariff of 1883. The decision rested on the popular definition that classifies vegetables by use, since tomatoes are served with dinner and not dessert. Botanically, the tomato is a fruit, specifically a berry.
Where did the tomato originate and when was it domesticated?
The tomato originated from western South America, with the red-fruited Solanum pimpinellifolium as its likely wild ancestor. Genomic analysis predicts the cultivated tomato originated around 7,000 years ago, about 5,000 BCE. By 500 BCE it was already being cultivated in southern Mexico.
Why were tomatoes once thought to be poisonous?
Tomatoes were assumed poisonous because they belong to the nightshade family, which includes deadly nightshade, tobacco, and the mandrake. In England the barber-surgeon John Gerard believed the tomato was poisonous in his 1597 Herbal, and his views kept it considered unfit to eat for many years in Britain and its North American colonies.
Why do modern tomatoes taste less sweet than older varieties?
Modern tomatoes lost flavor because breeders selected a mutant u phenotype in the mid-20th century so fruit would ripen uniformly red without a green ring around the stem. The u mutation produces defective chloroplasts that reduce sugar in the ripe fruit by 10 to 15%.
Who developed the commercial tomato in the United States?
Alexander W. Livingston, who lived from 1821 to 1898, developed the tomato as a commercial crop aiming for fruit smooth in contour, uniform in size, and sweet in flavor. He developed over seventeen varieties, introducing the Paragon in 1870 and the Acme in 1875.
How much tomato is produced in the world and which country leads?
World production of tomatoes reached 192 million tonnes in 2023. China led with 36% of the total, followed by India, Turkey, and the United States.