The tomato is the edible, often red fruit of the plant Solanum lycopersicum, commonly known as a tomato plant. Both the species and its use as a food originated in Mexico, and spread around the world following the Spanish colonization of the Americas. Its many varieties are now widely grown, sometimes in greenhouses in cooler climates.
The tomato is consumed in diverse ways, including raw, as an ingredient in many dishes, sauces, salads, and drinks. While it is botanically a fruit, it is considered a vegetable for culinary purposes (as well as by the United States Supreme Court, see Nix v. Hedden), which has caused some confusion. The fruit is rich in lycopene, which may have beneficial health effects.
The tomato belongs to the nightshade family. The plants typically grow to 1–3 meters (3–10 ft) in height and have a weak stem that often sprawls over the ground and vines over other plants. It is a perennial in its native habitat, although often grown outdoors in temperate climates as an annual. An average common tomato weighs approximately 100 grams.
- 1 History
- 2 Cultivation
- 3 Consumption
- 4 Botanical description
- 5 Botanical classification
- 6 Wild species
- 7 Genome sequencing
- 8 Breeding
- 9 Fruit or vegetable?
- 10 Names
- 11 Tomato records
- 12 Cultural impact
- 13 See also
- 14 References
- 15 Further reading
- 16 External links
Aztecs and other peoples in Mesoamerica used the fruit in their cooking. The exact date of domestication is unknown: by 500 BC, it was already being cultivated in southern Mexico and probably other areas.:13 The Pueblo people are thought to have believed that those who witnessed the ingestion of tomato seeds were blessed with powers of divination. The large, lumpy tomato, a mutation from a smoother, smaller fruit, originated in Mesoamerica, and may be the direct ancestor of some modern cultivated tomatoes.
Spanish conquistador Hernán Cortés may have been the first to transfer the small yellow tomato to Europe after he captured the Aztec city of Tenochtítlan, now Mexico City, in 1521, although Christopher Columbus, a Genoese working for the Spanish monarchy, may have taken them back as early as 1493. The earliest discussion of the tomato in European literature appeared in an herbal written in 1544 by Pietro Andrea Mattioli, an Italian physician and botanist, who suggested that a new type of eggplant had been brought to Italy that was blood red or golden color when mature and could be divided into segments and eaten like an eggplant—that is, cooked and seasoned with salt, black pepper, and oil. However it wasn't until ten years later that tomatoes were named in print by Mattioli as pomi d’oro, or "golden apple".:13
After the Spanish colonization of the Americas, the Spanish distributed the tomato throughout their colonies in the Caribbean. They also took it to the Philippines, from where it spread to southeast Asia and then the entire Asian continent. The Spanish also brought the tomato to Europe. It grew easily in Mediterranean climates, and cultivation began in the 1540s. It was probably eaten shortly after it was introduced, and was certainly being used as food by the early 17th century in Spain. The earliest discovered cookbook with tomato recipes was published in Naples in 1692, though the author had apparently obtained these recipes from Spanish sources.:17 In certain areas of Italy, such as Florence, however, the fruit was used solely as a tabletop decoration before it was incorporated into the local cuisine in the late 17th or early 18th century.
The recorded history of tomatoes in Italy dates back to 31 October 1548 when the house steward of Cosimo de' Medici, the grand duke of Tuscany, wrote to the Medici private secretary informing him that the basket of tomatoes sent from the grand duke's Florentine estate at Torre del Gallo "had arrived safely." Tomatoes were grown mainly as ornamentals early on after their arrival in Italy. For example, the Florentine aristocrat Giovanvettorio Soderini wrote how they "were to be sought only for their beauty" and were grown only in gardens or flower beds. The tomato's ability to mutate and create new and different varieties helped contribute to its success and spread throughout Italy. However, even in areas where the climate supported growing tomatoes, their proximity of growing to the ground suggested low status. They were not adopted as a staple of the peasant population because they were not as filling as other fruits already available. Additionally, both toxic and inedible varieties discouraged many people from attempting to consume or prepare them.
Tomatoes were not grown in England until the 1590s.:17 One of the earliest cultivators was John Gerard, a barber-surgeon.:17 Gerard's Herbal, published in 1597, and largely plagiarized from continental sources,:17 is also one of the earliest discussions of the tomato in England. Gerard knew the tomato was eaten in Spain and Italy.:17 Nonetheless, he believed it was poisonous:17 (in fact, the plant and raw fruit do have low levels of tomatine, but are not generally dangerous; see below). Gerard's views were influential, and the tomato was considered unfit for eating (though not necessarily poisonous) for many years in Britain and its North American colonies.:17 By the mid-18th century, tomatoes were widely eaten in Britain, and before the end of that century, the Encyclopædia Britannica stated the tomato was "in daily use" in soups, broths, and as a garnish.
The tomato was introduced to cultivation in the Middle East/Asia by John Barker, British consul in Aleppo circa 1799 to 1825. Nineteenth century descriptions of its consumption are uniformly as an ingredient in a cooked dish. In 1881, it is described as only eaten in the region "within the last forty years".
The tomato entered Iran through two separate routes; one was through Turkey and Armenia, and the other was through the Qajar royal family's frequent travels to France. The early name used for tomato in Iran was Armani badenjan (Armenian eggplant). Currently, the name used for tomato in Iran is gojeh farangi [French plum].
The earliest reference to tomatoes being grown in British North America is from 1710, when herbalist William Salmon reported seeing them in what is today South Carolina.:25 They may have been introduced from the Caribbean. By the mid-18th century, they were cultivated on some Carolina plantations, and probably in other parts of the Southeast as well. Possibly, some people continued to think tomatoes were poisonous at this time; and in general, they were grown more as ornamental plants than as food. Thomas Jefferson, who ate tomatoes in Paris, sent some seeds back to America.:28
Alexander W. Livingston was the first person who succeeded in upgrading the wild tomato, developing different breeds and stabilizing the plants. In the 1937 yearbook of the Federal Department of Agriculture, it was declared that "half of the major varieties were a result of the abilities of the Livingstons to evaluate and perpetuate superior material in the tomato". Livingston's first breed of tomato, the Paragon, was introduced in 1870. In 1875, he introduced the Acme, which was said to be involved in the parentage of most of the tomatoes introduced by him and his competitors for the next twenty-five years.
When Alexander W. Livingston had begun his attempts to develop the tomato as a commercial crop, his aim had been to grow tomatoes smooth in contour, uniform in size and having better flavor. One year, after many attempts, he passed through his fields, picking out particular tomato plants having distinct characteristics and heavy foliage. He saved the seeds carefully. The following spring he set two rows across his family garden located just below the hill and milk house. To his happy surprise, each plant bore perfect tomatoes like the parent vine. After five years, the fruit became fleshier and larger. In 1870, Alexander introduced the Paragon and tomato culture soon became a great enterprise in the county. Today, the crop is grown in every state in the Union. He eventually developed over seventeen different varieties of the tomato plant.
Because of the long growing season needed for this heat-loving crop, several states in the US Sun Belt became major tomato-producers, particularly Florida and California. In California, tomatoes are grown under irrigation for both the fresh fruit market and for canning and processing. The University of California, Davis (UC Davis) became a major center for research on the tomato. The C.M. Rick Tomato Genetics Resource Center at UC Davis is a gene bank of wild relatives, monogenic mutants and miscellaneous genetic stocks of tomato. The Center is named for the late Dr. Charles M. Rick, a pioneer in tomato genetics research. Research on processing tomatoes is also conducted by the California Tomato Research Institute in Escalon, California.
In California, growers have used a method of cultivation called dry-farming, especially with Early Girl tomatoes. This technique encourages the plant to send roots deep to find existing moisture in soil that retains moisture, such as clayey soil.
Modern commercial varieties
The poor taste and lack of sugar in modern garden and commercial tomato varieties resulted from breeding tomatoes to ripen uniformly red. This change occurred after discovery of a variety in the mid 20th century that ripened uniformly. This was widely cross-bred to produce red fruit without the typical green ring around the stem on uncross-bred varieties. Prior to general introduction of this trait, most tomatoes produced more sugar during ripening, and were sweeter and more flavorful.
The tomato is now grown worldwide for its edible fruits, with thousands of cultivars having been selected with varying fruit types, and for optimum growth in differing growing conditions. Cultivated tomatoes vary in size, from tomberries, about 5 mm in diameter, through cherry tomatoes, about the same 1–2 cm (0.4–0.8 in) size as the wild tomato, up to beefsteak tomatoes 10 cm (4 in) or more in diameter. The most widely grown commercial tomatoes tend to be in the 5–6 cm (2.0–2.4 in) diameter range. Most cultivars produce red fruit, but a number of cultivars with yellow, orange, pink, purple, green, black, or white fruit are also available. Multicolored and striped fruit can also be quite striking. Tomatoes grown for canning and sauces are often elongated, 7–9 cm (3–4 in) long and 4–5 cm (1.6–2.0 in) diameter; they are known as plum tomatoes, and have a lower water content. Roma-type tomatoes are important cultivars in the Sacramento Valley.
Tomatoes are one of the most common garden fruits in the United States and, along with zucchini, have a reputation for outproducing the needs of the grower.
Quite a few seed merchants and banks provide a large selection of heirloom seeds. The definition of an heirloom tomato is vague, but unlike commercial hybrids, all are self-pollinators that have bred true for 40 years or more.
About 150 million tons of tomatoes were produced in the world in 2009. China, the largest producer, accounted for about one quarter of the global output, followed by United States and India. For one variety, plum or processing tomatoes, California accounts for 90% of U.S. production and 35% of world production.
Within the EU, there are several areas that grow tomatoes with Protected Geographical Status. These include:
- Pomodoro di Pachino (PGI), in Sicily
- Pomodoro S. Marzano dell'Agro Sarnese-Nocerino (PDO), in south Italy
- Tomaten von der Insel Reichenau (PGI), from Reichenau Island, Germany
- Pomodorino del Piennolo del Vesuvio (PDO), in Mt Vesuvius area.
There are around 7500 tomato varieties grown for various purposes. Heirloom tomatoes are becoming increasingly popular, particularly among home gardeners and organic producers, since they tend to produce more interesting and flavorful crops at the cost of disease resistance and productivity. In 1973, Israeli scientists developed the world's first long shelf-life commercial tomato varieties.
Hybrid plants remain common, since they tend to be heavier producers, and sometimes combine unusual characteristics of heirloom tomatoes with the ruggedness of conventional commercial tomatoes.
Tomato varieties are roughly divided into several categories, based mostly on shape and size.
- "Slicing" or "globe" tomatoes are the usual tomatoes of commerce, used for a wide variety of processing and fresh eating.
- Beefsteak tomatoes are large tomatoes often used for sandwiches and similar applications. Their kidney-bean shape, thinner skin, and shorter shelf life makes commercial use impractical.
- Oxheart tomatoes can range in size up to beefsteaks, and are shaped like large strawberries.
- Plum tomatoes, or paste tomatoes (including pear tomatoes), are bred with a higher solids content for use in tomato sauce and paste, and are usually oblong.
- Pear tomatoes are pear-shaped, and are based upon the San Marzano types for a richer gourmet paste.
- Cherry tomatoes are small and round, often sweet tomatoes generally eaten whole in salads.
- Grape tomatoes, a more recent introduction, are smaller and oblong, a variation on plum tomatoes, and used in salads.
- Campari tomatoes are also sweet and noted for their juiciness, low acidity, and lack of mealiness. They are bigger than cherry tomatoes, but are smaller than plum tomatoes.
Early tomatoes and cool-summer tomatoes bear fruit even where nights are cool, which usually discourages fruit set. There are also varieties high in beta carotenes and vitamin A, hollow tomatoes and tomatoes that keep for months in storage.
Tomatoes are also commonly classified as determinate or indeterminate. Determinate, or bush, types bear a full crop all at once and top off at a specific height; they are often good choices for container growing. Determinate types are preferred by commercial growers who wish to harvest a whole field at one time, or home growers interested in canning. Indeterminate varieties develop into vines that never top off and continue producing until killed by frost. They are preferred by home growers and local-market farmers who want ripe fruit throughout the season. As an intermediate form, there are plants sometimes known as vigorous determinate or semideterminate; these top off like determinates, but produce a second crop after the initial crop. The majority of heirloom tomatoes are indeterminate, although some determinate heirlooms exist.
Most modern tomato cultivars are smooth surfaced, but some older tomato cultivars and most modern beefsteaks often show pronounced ribbing, a feature that may have been common to virtually all pre-Columbian cultivars. While virtually all commercial tomato varieties are red, some cultivars – especially heirlooms – produce fruit in other colors, including green, yellow, orange, pink, black, brown, ivory, white, and purple. Such fruits are not widely available in grocery stores, nor are their seedlings available in typical nurseries, but they can be bought as seed. Less common variations include fruit with stripes (Green Zebra), fuzzy skin on the fruit (Fuzzy Peach, Red Boar), multiple colors (Hillbilly, Burracker's Favorite, Lucky Cross), etc.
There is also a considerable gap between commercial and home-gardener cultivars. Home cultivars are often bred for flavor to the exclusion of all other qualities, while commercial cultivars are bred for factors like consistent size and shape, disease and pest resistance, suitability for mechanized picking and shipping, and ability to ripen after picking.
Tomatoes grow well with seven hours of sunlight a day. A fertilizer with an NPK ratio of 5-10-10 is often sold as tomato fertilizer or vegetable fertilizer, although manure and compost are also used.
Various heirloom tomato cultivars
Diseases and pests
Tomato cultivars vary widely in their resistance to disease. Modern hybrids focus on improving disease resistance over the heirloom plants. One common tomato disease is tobacco mosaic virus. Handling cigarettes and other tobacco products which are infected can result in transmission of the virus to tomato plants. Various forms of mildew and blight are also common tomato afflictions, which is why tomato cultivars are often marked with a combination of letters that refer to specific disease resistance. The most common letters are: V – verticillium wilt, F – fusarium wilt strain I, FF – fusarium wilt strain I and II, N – nematodes, T – tobacco mosaic virus, and A – alternaria.
Another particularly dreaded disease is curly top, carried by the beet leafhopper, which interrupts the lifecycle, ruining a nightshade plant as a crop. As the name implies, it has the symptom of making the top leaves of the plant wrinkle up and grow abnormally.
Some common tomato pests are stink bugs, cutworms, tomato hornworms and tobacco hornworms, aphids, cabbage loopers, whiteflies, tomato fruitworms, flea beetles, red spider mite, slugs, and Colorado potato beetles.
Tomato plants produce the plant peptide hormone systemin after an insect attack. Systemin activates defensive mechanisms, such as the production of protease inhibitors to slow the growth of insects. The hormone was first identified in tomatoes, but similar proteins have been identified in other species since.
Tomatoes serve, or are served by, a large variety of companion plants.
Additionally, the devastating tomato hornworm has a major predator in various parasitic wasps, whose larvae devour the hornworm, but whose adult form drinks nectar from tiny-flowered plants like umbellifers. Several species of umbellifer are therefore often grown with tomato plants, including parsley, queen anne's lace, and occasionally dill. These also attract predatory flies that attack various tomato pests.
Other plants with strong scents, like alliums (onions, chives, garlic) and mints (basil, oregano, spearmint) are simply thought to mask the scent of the tomato plant, making it harder for pests to locate it, or to provide an alternative landing point, reducing the odds of the pests from attacking the correct plant. These plants may also subtly impact the flavor of tomato fruit.
Ground cover plants, including mints, also stabilize moisture loss around tomato plants and other solaneae, which come from very humid climates, and therefore may prevent moisture-related problems like blossom end rot.
Finally, tap-root plants like dandelions break up dense soil and bring nutrients from down below a tomato plant's reach, possibly benefiting their companion.
Tomato plants, on the other hand, protect asparagus from asparagus beetles, because they contain solanum that kills this pest, while asparagus plants (as well as marigolds) contain a chemical that repels root nematodes known to attack tomato plants.
In the wild, original state, tomatoes required cross-pollination; they were much more self-incompatible than domestic cultivars. As a floral device to reduce selfing, the pistil of wild tomatoes extends farther out of the flower than today's cultivars. The stamens were, and remain, entirely within the closed corolla.
As tomatoes were moved from their native areas, their traditional pollinators, (probably a species of halictid bee) did not move with them. The trait of self-fertility became an advantage, and domestic cultivars of tomato have been selected to maximize this trait.
This is not the same as self-pollination, despite the common claim that tomatoes do so. That tomatoes pollinate themselves poorly without outside aid is clearly shown in greenhouse situations, where pollination must be aided by artificial wind, vibration of the plants (one brand of vibrator is a wand called an "electric bee" that is used manually), or more often today, by cultured bumblebees. The anther of a tomato flower is shaped like a hollow tube, with the pollen produced within the structure, rather than on the surface, as in most species. The pollen moves through pores in the anther, but very little pollen is shed without some kind of outside motion. The best source of outside motion is a sonicating bee, such as a bumblebee, or the original wild halictid pollinator. In an outside setting, wind or animals provide sufficient motion to produce commercially viable crops.
Hydroponic and greenhouse cultivation
Tomatoes are often grown in greenhouses in cooler climates, and there are cultivars such as the British 'Moneymaker' and a number of cultivars grown in Siberia that are specifically bred for indoor growing. In more temperate climates, it is not uncommon to start seeds in greenhouses during the late winter for future transplant.
Greenhouse tomato production in large-acreage commercial greenhouses and owner-operator stand-alone or multiple-bay greenhouses is on the increase, providing fruit during those times of the year when field-grown fruit is not readily available. Smaller sized fruit (cherry and grape), or cluster tomatoes (fruit-on-the-vine) are the fruit of choice for the large commercial greenhouse operators while the beefsteak varieties are the choice of owner-operator growers.
Hydroponic tomatoes are also available, and the technique is often used in hostile growing environments, as well as high-density plantings.
Picking and ripening
To facilitate transportation and storage, tomatoes are often picked unripe (green) and ripened in storage with ethylene. Unripe tomatoes are firm. As they ripen they soften until reaching the ripe state where they are red or orange in color and slightly soft to the touch. Ethylene is a hydrocarbon gas produced by many fruits that acts as the molecular cue to begin the ripening process. Tomatoes ripened in this way tend to keep longer, but have poorer flavor and a mealier, starchier texture than tomatoes ripened on the plant. They may be recognized by their color, which is more pink or orange than the other ripe tomatoes' deep red, depending on variety.
A machine-harvestable variety of tomato (the "square tomato") was developed in the 1950s by University of California, Davis's Gordie C. Hanna, which, in combination with the development of a suitable harvester, revolutionized the tomato-growing industry. This type of tomato is grown commercially near processing plants which produce canned tomatoes, tomato sauce, and tomato paste. They are harvested when ripe and are flavorful when picked. They are harvested 24/7 during a season of 12 to 14 weeks and are immediately transported to packing plants which operate on the same basis. California is a center of this sort of commercial tomato production and produces about 1/3 of the processed tomatoes produced in the world.
In 1994, Calgene introduced a genetically modified tomato called the FlavrSavr, which could be vine ripened without compromising shelf life. However, the product was not commercially successful, and was sold only until 1997.
"Tomatoes on the vine" are determinate varieties that are ripened or harvested with the fruits still connected to a piece of vine. These tend to have more flavor than artificially ripened tomatoes (at a price premium).
Slow-ripening cultivars of tomato have been developed by crossing a non-ripening cultivar with ordinary cultivars. Cultivars were selected whose fruits have a long shelf life and at least reasonable flavor.
At home, fully ripe tomatoes can be stored in the refrigerator, but are best kept at room temperature. Tomatoes stored cold remain edible, but tend to lose their flavor permanently; thus, "Never Refrigerate" stickers are sometimes placed on tomatoes in supermarkets. Tomatoes stored stem down may also keep from rotting too quickly.
Tomatoes that have been modified using genetic engineering have been developed, and although none are commercially available now, they have been in the past. The first commercially available genetically modified food was a variety of tomato named (the Flavr Savr), which was engineered to have a longer shelf life. Scientists are continuing to develop tomatoes with new traits not found in natural crops, such as increased resistance to pests or environmental stresses. Other projects aim to enrich tomatoes with substances that may offer health benefits or provide better nutrition.
The tomato is now grown and eaten around the world. It is used in diverse ways, including raw in salads, and processed into ketchup or tomato soup. Unripe green tomatoes can also be breaded and fried, used to make salsa, or pickled. Tomato juice is sold as a drink, and is used in cocktails such as the Bloody Mary.
Tomatoes are acidic, making them especially easy to preserve in home canning whole, in pieces, as tomato sauce or paste. The fruit is also preserved by drying, often in the sun, and sold either in bags or in jars with oil.
Tomatoes are used extensively in Mediterranean cuisine. They are a key ingredient in pizza, and are commonly used in pasta sauces. They are also used in gazpacho (Spanish cuisine) and pa amb tomàquet (Catalan cuisine).
|Nutritional value per 100 g (3.5 oz)|
|Energy||74 kJ (18 kcal)|
|- Sugars||2.6 g|
|- Dietary fiber||1.2 g|
|Vitamin A equiv.||42 μg (5%)|
|- beta-carotene||449 μg (4%)|
|- lutein and zeaxanthin||123 μg|
|Thiamine (vit. B1)||0.037 mg (3%)|
|Niacin (vit. B3)||0.594 mg (4%)|
|Vitamin B6||0.08 mg (6%)|
|Vitamin C||14 mg (17%)|
|Vitamin E||0.54 mg (4%)|
|Vitamin K||7.9 μg (8%)|
|Magnesium||11 mg (3%)|
|Manganese||0.114 mg (5%)|
|Phosphorus||24 mg (3%)|
|Potassium||237 mg (5%)|
|Link to USDA Database entry|
Percentages are roughly approximated
using US recommendations for adults.
Source: USDA Nutrient Database
Tomatoes are now eaten freely throughout the world. They contain the carotene lycopene, one of the most powerful natural antioxidants. In some studies, lycopene, especially in cooked tomatoes, has been found to help prevent prostate cancer, but other research contradicts this claim. Lycopene has also been shown to improve the skin's ability to protect against harmful UV rays. A study done by researchers at Manchester and Newcastle universities revealed that tomato can protect against sunburn and help keeping the skin looking youthful. Natural genetic variation in tomatoes and their wild relatives has given a genetic plethora of genes that produce lycopene, carotene, anthocyanin, and other antioxidants. Tomato varieties are available with double the normal vitamin C (Doublerich), 40 times normal vitamin A (97L97), high levels of anthocyanin (resulting in blue tomatoes), and two to four times the normal amount of lycopene (numerous available cultivars with the high crimson gene).
Lycopene has also been shown to protect against oxidative damage in many epidemiological and experimental studies. In addition to its antioxidant activity, other metabolic effects of lycopene have also been demonstrated. The richest source of lycopene in the diet is tomato and tomato derived products. Tomato consumption has been associated with decreased risk of breast cancer, head and neck cancers and might be strongly protective against neurodegenerative diseases. Tomatoes, tomato sauces and puree are said to help lower urinary tract symptoms (BPH) and may have anticancer properties. Tomato consumption might be beneficial for reducing cardiovascular risk associated with type 2 diabetes.
Tomatoes keep best unwashed at room temperature and out of direct sunlight. It is not recommended to refrigerate as this can harm the flavor. Tomatoes that are not yet ripe can be kept in a paper bag till ripening. Storing stem down can prolong shelf life. 
Leaves, stems, and green unripe fruit of the tomato plant contain small amounts of the toxic alkaloid tomatine. They also contain solanine, a toxic alkaloid found in potato leaves and other plants in the nightshade family. Use of tomato leaves in tea (tisane) has been responsible for at least one death. However, levels of tomatine in foliage and green fruit are generally too small to be dangerous unless large amounts are consumed, for example, as greens. Small amounts of tomato foliage are sometimes used for flavoring without ill effect, and the green fruit is sometimes used for cooking, particularly as fried green tomatoes. Compared to potatoes the amount of solanine in green or ripe tomatoes is low; however, even in the case of potatoes while solanine poisoning resulting from dosages several times normal human consumption has been demonstrated, actual cases of poisoning resulting from excessive consumption of potatoes that have high concentration of solanine are rare.
Tomato plants can be toxic to dogs if they eat large amounts of the fruit, or chew plant material.
On 30 October 2006, the U.S. Centers for Disease Control and Prevention (CDC) announced tomatoes might have been the source of a salmonellosis outbreak causing 172 illnesses in 18 states. Tomatoes have been linked to seven salmonella outbreaks since 1990.
The 2008 United States salmonellosis outbreak caused the removal of tomatoes from stores and restaurants across the United States and parts of Canada, although other foods, including jalapeño and serrano peppers, may have been involved.
Tomato plants are vines, initially decumbent, typically growing six feet or more above the ground if supported, although erect bush varieties have been bred, generally three feet tall or shorter. Indeterminate types are "tender" perennials, dying annually in temperate climates (they are originally native to tropical highlands), although they can live up to three years in a greenhouse in some cases. Determinate types are annual in all climates.
Tomato plants are dicots, and grow as a series of branching stems, with a terminal bud at the tip that does the actual growing. When that tip eventually stops growing, whether because of pruning or flowering, lateral buds take over and grow into other, fully functional, vines.
Tomato vines are typically pubescent, meaning covered with fine short hairs. These hairs facilitate the vining process, turning into roots wherever the plant is in contact with the ground and moisture, especially if the vine's connection to its original root has been damaged or severed.
Most tomato plants have compound leaves, and are called regular leaf (RL) plants, but some cultivars have simple leaves known as potato leaf (PL) style because of their resemblance to that particular relative. Of RL plants, there are variations, such as rugose leaves, which are deeply grooved, and variegated, angora leaves, which have additional colors where a genetic mutation causes chlorophyll to be excluded from some portions of the leaves.
The leaves are 10–25 centimetres (4–10 in) long, odd pinnate, with five to 9 leaflets on petioles, each leaflet up to 8 centimetres (3 in) long, with a serrated margin; both the stem and leaves are densely glandular-hairy.
Their flowers, appearing on the apical meristem, have the anthers fused along the edges, forming a column surrounding the pistil's style. Flowers in domestic cultivars tend to be self-fertilizing. The flowers are 1–2 centimetres (0.4–0.8 in) across, yellow, with five pointed lobes on the corolla; they are borne in a cyme of three to 12 together.
Tomato fruit is classified as a berry. As a true fruit, it develops from the ovary of the plant after fertilization, its flesh comprising the pericarp walls. The fruit contains hollow spaces full of seeds and moisture, called locular cavities. These vary, among cultivated species, according to type. Some smaller varieties have two cavities, globe-shaped varieties typically have three to five, beefsteak tomatoes have a great number of smaller cavities, while paste tomatoes have very few, very small cavities.
For propagation, the seeds need to come from a mature fruit, and be dried or fermented before germination.
In 1753, Linnaeus placed the tomato in the genus Solanum (alongside the potato) as Solanum lycopersicum. In 1768, Philip Miller moved it to its own genus, naming it Lycopersicon esculentum. This name came into wide use, but was in breach of the plant naming rules. Technically, the combination Lycopersicon lycopersicum (L.) H.Karst. would be more correct, but this name (published in 1881) has hardly ever been used (except in seed catalogs, which frequently used it and still do).
Genetic evidence has now shown that Linnaeus was correct to put the tomato in the genus Solanum, making Solanum lycopersicum the correct name. Both names, however, will probably be found in the literature for some time. Two of the major reasons some still consider the genera separate are the leaf structure (tomato leaves are markedly different from any other Solanum), and the biochemistry (many of the alkaloids common to other Solanum species are conspicuously absent in the tomato). Hybrids of tomato and diploid potato can be created in the lab by somatic fusion, and are partially fertile, providing evidence of the close relationship between these species.
Including Solanum lycopersicum, there are currently 13 species recognized in Solanum section Lycopersicon. Three of these species—S. Cheesmaniae, S. Galapagense, and S. Pimpinellifolium—are fully cross compatible with domestic tomato. Four more species—S. chmielewskii, S. habrochaites, S. neorickii, and S. pennelli—can be readily crossed with domestic tomato, with some limitations. Five species—S. arcanum, S. chilense, S. corneliomulleri, S. huaylasense, and S. peruvianum—can be crossed with domestic tomato with difficulty and usually require embryo rescue to produce viable plants. The Lycopersicon section has not been fully sampled within wild species in the South American range, so new species may be added in the future.
Solanum section Lycopersicoides and section Juglandifolium are represented by two species each that are considered bridge species genetically intermediate between tomato and non-tuber bearing potato species. S. Lycopersicoides can be crossed with domestic tomato and introgression lines  have been developed. This species was significant in moving the domestic tomato from separate genus status into the Solanum group because it directly links the tomato into the potato family.
An international consortium of researchers from 10 countries, among them researchers from the Boyce Thompson Institute for Plant Research, began sequencing the tomato genome in 2004, and is creating a database of genomic sequences and information on the tomato and related plants. A prerelease version of the genome was made available in December 2009. The genomes of its mitochondria and chloroplasts are also being sequenced as part of the project. The complete genome for the cultivar Heinz 1706 was published on 31 May 2012 in Nature. Since many other fruits, like strawberries, apples, melons, and bananas share the same characteristics and genes, researchers stated the published genome could help to improve food quality, food security and reduce costs of all of these fruits.
Active breeding programs are ongoing by individuals, universities, corporations, and organizations. The Tomato Genetic Resource Center, Germplasm Resources Information Network, AVRDC, and numerous seed banks around the world store seed representing genetic variations of value to modern agriculture. These seed stocks are available for legitimate breeding and research efforts. While individual breeding efforts can produce useful results, the bulk of tomato breeding work is at universities and major agriculture-related corporations. These efforts have resulted in significant regionally adapted breeding lines and hybrids, such as the Mountain series from North Carolina. Corporations including Heinz, Monsanto, BHNSeed, Bejoseed, etc., have breeding programs that attempt to improve production, size, shape, color, flavor, disease tolerance, pest tolerance, nutritional value, and numerous other traits.
Fruit or vegetable?
Botanically, a tomato is a fruit: the ovary, together with its seeds, of a flowering plant. However, the tomato has a much lower sugar content than other edible fruits, and is therefore not as sweet. Typically served as part of a salad or main course of a meal, rather than at dessert, it is considered a vegetable for most culinary uses. One exception is that tomatoes are treated as a fruit in home canning practices: they are acidic enough to process in a water bath rather than a pressure cooker as vegetables require. Tomatoes are not the only food source with this ambiguity: green beans, eggplants, cucumbers, and squashes of all kinds (such as zucchini and pumpkins) are all botanically fruits, yet cooked as vegetables.
This dispute has led to legal speculation in the United States. In 1887, U.S. tariff laws that imposed a duty on vegetables, but not on fruits, caused the tomato's status to become a matter of legal importance. The U.S. Supreme Court settled this controversy on 10 May 1893, by declaring that the tomato is a vegetable, based on the popular definition that classifies vegetables by use, that they are generally served with dinner and not dessert (Nix v. Hedden (149 U.S. 304)). The holding of this case applies only to the interpretation of the Tariff Act of 3 March 1883, and the court did not purport to reclassify the tomato for botanical or other purposes.
Tomatoes have been designated the state vegetable of New Jersey. Arkansas took both sides by declaring the South Arkansas Vine Ripe Pink Tomato both the state fruit and the state vegetable in the same law, citing both its culinary and botanical classifications. In 2009, the state of Ohio passed a law making the tomato the state's official fruit. Tomato juice has been the official beverage of Ohio since 1965. A.W. Livingston, of Reynoldsburg, Ohio, played a large part in popularizing the tomato in the late 19th century; his efforts are commemorated in Reynoldsburg with an annual Tomato Festival.
The scientific species epithet lycopersicum means "wolf peach", and comes from German werewolf myths. These legends said that deadly nightshade was used by witches and sorcerers in potions to transform themselves into werewolves, so the tomato's similar, but much larger, fruit was called the "wolf peach" when it arrived in Europe.
The Aztecs called the fruit xitomatl (pronounced [ʃiːˈtomatɬ]), meaning plump thing with a navel. Other Mesoamerican peoples, including the Nahuas, took the name as tomatl, from which most western European languages derived their names for "tomato". However, the Italian word, pomodoro (from pomo d'oro "apple of gold") was borrowed into Polish, and via Russian, into several other languages. Similarly, the now rare German term Paradeisapfel (for "apple of paradise") is still heard in the form paradeiser in the Bavarian and Austrian dialects, and was borrowed into modern Hungarian, Slovenian and Serbian.
The pronunciation of tomato differs in different English-speaking countries; the two most common variants are // tə-MAH-toh and // tə-MAY-toh. Speakers from the British Isles and most of the Commonwealth typically say //, while most North American speakers usually say //.
The word's dual pronunciations were immortalized in Ira and George Gershwin's 1937 song Let's Call the Whole Thing Off ("You like // and I like // / You like // and I like //") and have become a symbol for nitpicking pronunciation disputes. In this capacity, it has even become an American and British slang term: saying "// //" when presented with two choices can mean "What's the difference?" or "It's all the same to me."
The heaviest tomato ever, weighing 3.51 kg (7 lb 12 oz), was of the cultivar 'Delicious', grown by Gordon Graham of Edmond, Oklahoma in 1986.[unreliable source?] The largest tomato plant grown was of the cultivar 'Sungold' and reached 19.8 m (65 ft) in length, grown by Nutriculture Ltd (UK) of Mawdesley, Lancashire, UK, in 2000.
The massive "tomato tree" growing inside the Walt Disney World Resort's experimental greenhouses in Lake Buena Vista, Florida may be the largest single tomato plant in the world. The plant has been recognized as a Guinness World Record Holder, with a harvest of more than 32,000 tomatoes and a total weight of 522 kg (1,151 lb). It yields thousands of tomatoes at one time from a single vine. Yong Huang, Epcot's manager of agricultural science, discovered the unique plant in Beijing, China. Huang brought its seeds to Epcot and created the specialized greenhouse for the fruit to grow. The vine grows golf ball-sized tomatoes, which are served at Walt Disney World restaurants.
The world record-setting tomato tree can no longer be seen by guests along the Living With the Land boat ride at Epcot, as the tree developed a disease and was removed in April 2010 after approximately 13 months of life.
The town of Buñol, Spain, annually celebrates La Tomatina, a festival centered on an enormous tomato fight. Tomatoes are a popular "nonlethal" throwing weapon in mass protests, and there was a common tradition of throwing rotten tomatoes at bad performers on a stage during the 19th century; today this is usually referenced as a metaphor. Embracing it for this protest connotation, the Dutch Socialist party adopted the tomato as their logo.
Several US states have adopted the tomato as a state fruit or vegetable (see above).
- "Solanaceae Source: Phylogeny of the genus Solanum". Natural History Museum. "Molecular phylogenetic analyses have established that the formerly segregate genera Lycopersicon, Cyphomandra, Normania, and Triguera are nested within Solanum, and all species of these four genera have been transferred to Solanum"
- "Tomaat september 2010, RZ Seeds & Services". "Het gemiddeld vruchtgewicht ligt tussen de 102 en 105 gram en de kwaliteit is goed." 2010 rijkzwaan.nl
- "Enza Zaden – Teeltnieuws". "Het gemiddelde vruchtgewicht van Ingar ligt tussen 100–110 gram." 6 August 2009 enzazaden.nl
- Smith, A. F. (1994). The Tomato in America: Early History, Culture, and Cookery. Columbia SC, USA: University of South Carolina Press. ISBN 1-57003-000-6.[page needed]
- Donnelly, L. (26 October 2008). "Killer Tomatoes". The East Hampton Star.
- Gentilcore, David (2010) A History of the Tomato in Italy Pomodoro! New York, NY: Columbia University Press, ISBN 023115206X.
- "British Consuls in Aleppo – Your Archives". Yourarchives.nationalarchives.gov.uk. 26 January 2009. Retrieved 2 April 2009.
- "Syria under the last five Turkish Sultans". Appletons' Journal 1. D. Appleton and Co. 1876. p. 519.
- The Friend 54. 1881. p. 223.
- About Reynoldsburg. ci.reynoldsburg.oh.us
- "C. M. Rick Tomato Genetics Resource Center". UC Davis. Retrieved 2 April 2009.
- "UC Newsroom, UC Davis Tomato Geneticist Charles Rick Dies at 87". University of California. 8 May 2002. Retrieved 2 April 2009.
- California Tomato Research Institute. tomatonet.org
- "Uniform ripening Encodes a Golden 2-like Transcription Factor Regulating Tomato Fruit Chloroplast Development". Science 336 (6089): 1711–1715. 29 June 2012. doi:10.1126/science.1222218. Retrieved 29 June 2012. "Modern tomato...varieties are bred for uniform ripening (u) light green fruit phenotypes to facilitate harvests of evenly ripened fruit. U encodes a...factor...which determines chlorophyll accumulation and distribution in developing fruit. [The factor] influences photosynthesis in developing fruit, contributing to mature fruit characteristics and suggesting that selection of u inadvertently compromised ripe fruit quality in exchange for desirable production traits."
- Kolata, Gina (28 June 2012). "Flavor Is Price of Scarlet Hue of Tomatoes, Study Finds". The New York Times. Retrieved 29 June 2012.
- Allen, A. (August 2008). "A Passion for Tomatoes". Smithsonian magazine.
- Hartz, T. et al.. "Processing Tomato Production in California". UC Vegetable Research and Information Center.
- "Production of Tomato by countries". Food and Agriculture Organization. 2011. Retrieved 23 August 2013.
- Yissum: Seed improvement technology. Docs.google.com. Retrieved on 5 September 2013.
- Pfleger, F. L.; Zeyen, R. J. (2008). "Tomato-Tobacco Mosaic Virus Disease". University of Minnesota Extension. Retrieved 23 June 2012.
- Hahn, J.; Fetzer, J. (2009). "Slugs in Home Gardens". University of Minnesota Extension. Retrieved 23 June 2012.
- Narvaez-Vasquez, J.; Orozco-Cardenas, M. L. (2008). "15 Systemins and AtPeps: Defense-related Peptide Signals". In Schaller, A. Induced Plant Resistance to Herbivory. ISBN 978-1-4020-8181-1.
- Carrots Love Tomatoes.
- Tomato Casual » Boost Your Tomatoes with Companion Planting! – Part 1. Tomatocasual.com (6 May 2008). Retrieved on 5 September 2013.
- Vegetable Garden Companion Planting – Plant Tomatoes, Borage, and Squash Together. Organicgardening.about.com (16 July 2013). Retrieved on 5 September 2013.
- Companion Planting. Ghorganics.com. Retrieved on 5 September 2013.
- Companion Planting. Homeandgardensite.com (15 January 2009). Retrieved on 5 September 2013.
- Sharma, V. P. (16 January 2012). Nature at Work – the Ongoing Saga of Evolution. Springer. p. 41. ISBN 978-81-8489-991-7.
- Jones, J. Benton. "Growing in the Greenhouse". growtomatoes.com. Retrieved 14 August 2012.
- Bittman, Mark (14 June 2011). "The True Cost of Tomatoes".
- Bittman, Mark (17 August 2013). "Not All Industrial Food Is Evil". The New York Times. Retrieved 18 August 2013.
- "Selecting, Storing and Serving Ohio Tomatoes, HYG-5532-93". Ohio State University. Retrieved 27 October 2008.
- Store Tomatoes Stem-End Down to Keep Them from Rotting Too Quickly. Lifehacker.com. Retrieved on 5 September 2013.
- Redenbaugh, K.; Hiatt, B.; Martineau, B.; Kramer, M.; Sheehy, R.; Sanders, R.; Houck, C.; Emlay, D. (1992). Safety Assessment of Genetically Engineered Fruits and Vegetables: A Case Study of the Flavr Savr Tomato. CRC Press. p. 288.
- "Health benefits of tomatoes". Retrieved 24 May 2007.
- "No magic tomato? Study breaks link between lycopene and prostate cancer prevention". Retrieved 24 May 2007.
- "Tomato dishes 'may protect skin'". BBC News. 28 April 2008. Retrieved 6 January 2010.
- Maccrae, F. "The secret of eternal youth? Try a tomato". Retrieved 28 April 2008.
- Mourvaki, E.; Gizzi, S.; Rossi, R.; Rufini, S. (2005). "Passionflower Fruit — A "New" Source of Lycopene?". Journal of Medicinal Food 8 (1): 104–106. PMID 15857218.
- Zhang, C. X.; Ho, S. C.; Chen, Y. M.; Fu, J. H.; Cheng, S. Z.; Lin, F. Y. (2009). "Greater vegetable and fruit intake is associated with a lower risk of breast cancer among Chinese women". International Journal of Cancer 125 (1): 181–188. doi:10.1002/ijc.24358. PMID 19358284.
- Freedman, N. D.; Park, Y.; Subar, A. F.; Hollenbeck, A. R.; Leitzmann, M. F.; Schatzkin, A.; Abnet, C. C. (2008). "Fruit and vegetable intake and head and neck cancer risk in a large United States prospective cohort study". International Journal of Cancer 122 (10): 2330–2336. doi:10.1002/ijc.23319. PMID 18092323.
- Rao, A. V.; Balachandran, B. (2002). "Role of oxidative stress and antioxidants in neurodegenerative diseases". Nutritional Neuroscience 5 (5): 291–309. doi:10.1080/1028415021000033767. PMID 12385592.
- Fall, P. A.; Fredrikson, M.; Axelson, O.; Granérus, A. K. (1999). "Nutritional and occupational factors influencing the risk of Parkinson's disease: A case-control study in southeastern Sweden". Movement Disorders 14 (1): 28–37. doi:10.1002/1531-8257(199901)14:1<28::AID-MDS1007>3.0.CO;2-O. PMID 9918341.
- Suganuma, H.; Hirano, T.; Arimoto, Y.; Inakuma, T. (2002). "Effect of tomato intake on striatal monoamine level in a mouse model of experimental Parkinson's disease". Journal of Nutritional Science and Vitaminology 48 (3): 251–254. doi:10.3177/jnsv.48.251. PMID 12350086.
- Polívková, Z.; Šmerák, P.; Demová, H.; Houška, M. (2010). "Antimutagenic Effects of Lycopene and Tomato Purée". Journal of Medicinal Food 13 (6): 1443–1450. PMID 20874227.
- Shidfar, F.; Froghifar, N.; Vafa, M.; Rajab, A.; Hosseini, S.; Shidfar, S.; Gohari, M. (2011). "The Effects of Tomato Consumption on Serum Glucose, Apolipoprotein B, Apolipoprotein A-I, Homocysteine and Blood Pressure in Type 2 Diabetic Patients". International Journal of Food Sciences and Nutrition 62 (3): 289–294. PMID 21138408.
- Parnell, Tracy L.; Suslow, Trevor V.; Harris, Linda J. (March 2004). "Tomatoes:Safe Methods to Store, Preserve, and Enjoy". ANR Catalog. University of California: Division of Agriculture and Natural Resources. Retrieved 18 February 2013.
- "Vegetables". Canadian Produce Marketing Association Website. Canadian Produce Marketing Association. Retrieved 18 February 2013.
- How To Cook. Cooks Illustrated (1 July 2008). Retrieved on 5 September 2013.
- Mcgee, H. (29 July 2009). "Accused, Yes, but Probably Not a Killer". The New York Times. Retrieved 26 March 2010.
- Barceloux, D. G. (2009). "Potatoes, Tomatoes, and Solanine Toxicity (Solanum tuberosum L., Solanum lycopersicum L.)". Disease-a-Month 55 (6): 391–402. doi:10.1016/j.disamonth.2009.03.009. PMID 19446683.
- "Executive Summary Chaconine and Solanine: 6.0 through 8.0". NIH.
- Brevitz, B. (2004). Hound Health Handbook: The Definitive Guide to Keeping your Dog Happy. Workman Publishing Company. p. 404. ISBN 076112795X.
- "CDC Probes Salmonella Outbreak, Health Officials Say Bacteria May Have Spread Through Some Form Of Produce". CBS News. 30 October 2006. Retrieved 27 October 2008.
- "A selection of North American tomato related outbreaks from 1990–2005". Food Safety Network. 30 October 2006. Retrieved 20 July 2010.
- "Tomatoes taken off menus". Calgary Herald. 11 June 2008. Retrieved 20 July 2010.
- Peet, M. "Crop Profiles – Tomato". Retrieved 27 October 2008.[self-published source?]
- "Are there different types of tomato leaves?". IVillage. Retrieved 27 October 2008.[unreliable source?]
- Acquaah, G. (2002). Horticulture: Principles and Practices. New Jersey: Prentice Hall.
- Lycopersicon esculentum, International Plant Name Index
- Peralta, I. E.; Spooner, D. M. (2001). "Granule-bound starch synthase (GBSSI) gene phylogeny of wild tomatoes (Solanum L. section Lycopersicon (Mill.) Wettst. subsection Lycopersicon)". American Journal of Botany 88 (10): 1888–1902. doi:10.2307/3558365. JSTOR 3558365. PMID 21669622.
- Jacobsen, E.; Daniel, M. K.; Bergervoet-van Deelen, J. E. M.; Huigen, D. J.; Ramanna, M. S. (1994). "The first and second backcross progeny of the intergeneric fusion hybrids of potato and tomato after crossing with potato". TAG Theoretical and Applied Genetics 88 (2): 181–186. doi:10.1007/BF00225895.
- Tomato Genetics Resource Center – Solanum lycopersicoides introgression lines. Tgrc.ucdavis.edu. Retrieved on 5 September 2013.
- Mueller, L. "International Tomato Genome Sequencing Project". Sol Genomics Network. Retrieved 21 October 2009.
- Ramanujan, K. (30 January 2007). "Tomato genome project gets $1.8M". News.cornell.edu. Retrieved 27 October 2008.
- "Tomato Genome Shotgun Sequence Prerelease".
- Sato, S.; Tabata, S.; Hirakawa, H.; Asamizu, E.; Shirasawa, K.; Isobe, S.; Kaneko, T.; Nakamura, Y.; Shibata, D. (2012). "The tomato genome sequence provides insights into fleshy fruit evolution". Nature 485 (7400): 635–641. doi:10.1038/nature11119. PMC 3378239. PMID 22660326.
- Tomato genome is sequenced for the first time. Rdmag.com. Retrieved on 5 September 2013.
- "Vegetarians in Paradise/Tomato History, Tomato Nutrition, Tomato Recipe". Vegparadise.com. Retrieved 2 April 2009.
- Hammerschmidt, D.; Franklin, M. (2005). "About the cover illustration". Journal of Laboratory and Clinical Medicine 146 (4): 251–252. doi:10.1016/j.lab.2005.08.010. PMID 16194687.
- "Curiosities of I-5, facts about King and the benefits of volunteers". Chester Progressive. 16 January 2008.
- A World Record Breaker. Nutriculture.com. Retrieved on 5 September 2013.
- Walt Disney World News. wdwnews.com
- "Spain's tomato fighters see red". ITV. 30 August 2007. Retrieved 2 April 2009.
- David Gentilcore. Pomodoro! A History of the Tomato in Italy (Columbia University Press, 2010), scholarly history