Wild potato species occur from the United States to Uruguay and Chile. Genetic testing of the wide variety of cultivars and wild species suggest that the potato has a single origin in the area of southern Peru, and that the single ancestor of all potatoes in the world, the Solanum brevicaule, originiated more than 10,000 years ago in Peru's portion of lake Titicaca. Today, over 99% of all cultivated potato varieties worldwide are descendants of a subspecies indigenous to south-central Chile. Based on historical records, local agriculturalists, and DNA analyses, the most widely cultivated variety worldwide, Solanum tuberosum tuberosum, is believed to be indigenous to Chiloé Archipelago where it was cultivated by the indigenous people.
The potato was introduced to Europe in 1536, and subsequently by European mariners to territories and ports throughout the world. Thousands of varieties persist in the Andes, where over 100 varieties might be found in a single valley, and a dozen or more might be maintained by a single agricultural household. Once established in Europe, the potato soon became an important food staple and field crop. But lack of genetic diversity, due to the fact that very few varieties were initially introduced, left the crop vulnerable to disease. In 1845, a plant disease known as late blight, caused by the fungus-like oocmycete Phytophthora infestans, spread rapidly through the poorer communities of western Ireland, resulting in the crop failures that led to the Great Irish Famine.
The annual diet of an average global citizen in the first decade of the twenty-first century would include about 33 kilograms (or 73 lbs.) of potato. However, the local importance of potato is extremely variable and rapidly changing. The potato remains an essential crop in Europe (especially eastern and central Europe), where per capita production is still the highest in the world, but the most rapid expansion of potato over the past few decades has occurred in southern and eastern Asia. China is now the world’s largest potato producing country, and nearly a third of the world’s potatoes are harvested in China and India. More generally, the geographic shift of potato production has been away from wealthier countries toward lower-income areas of the world.
The English word potato comes from Spanish patata (the name used in Spain). The Spanish Royal Academy says the Spanish word is a compound of the Taino batata (sweet potato) and the Quechua papa (potato). This probably indicates that originally, the potato was regarded as a type of sweet potato rather than the other way around, despite the fact that there is actually no close relationship between the two plants at all. Potatoes are occasionally referred to as Irish potatoes in the English speaking world, this term originated to distinguish them from sweet potatoes.
Romanian cartof, Ukrainian картопля (kartóplja), Bulgarian картоф (kartof), Russian картофель (kartofel), German and Danish kartoffel, Icelandic kartafla, Latvian kartupelis, and Estonian kartul (as well as many other similar names in various languages) all derive from the Italian word tartufoli, which was given to potato because of its similarity to truffles (Italian: tartufo). Although the current Italian term for the potato is patata.
Another common name is "ground apple": pomme de terre in French, aardappel in Dutch, תפוח אדמה in Hebrew (often written just as תפוד), and Erdapfel in Austrian German. An analogous name is Finnish as peruna, which comes from the old Swedish term jordpäron "earth pear". In 16th century French, pomme meant "fruit", thus pomme de terre meant "ground fruit" and was probably literally loan translated to other languages when potatoes were introduced. In Polish potato is called just ziemniaki or in some regions "kartofle", and in Slovak zemiak, from the word for "ground". In Farsi and Persian it is called "seeb-i zameen" which also translates into 'ground apple'.
Different names for the potato developed in China's various regions. The most widely used names in Standard Mandarin are "horse-bell yam" "earth bean" and "foreign taro" (). The Indonesian word is kentang.
Potato plants are herbaceous perennials that grow about 60cm high, depending on variety, the culms dying back after flowering. They bear white to purple flowers with yellow stamens resembling those of other Solanaceous species such as tomato and aubergine. Potatoes are cross-pollinated mostly by insects, including bumblebees that carry pollen from other potato plants, but a substantial amount of self-fertilizing occurs as well.
After potato plants flower, some varieties will produce small green fruits that resemble green cherry tomatoes, each containing up to 300 true seeds. Potato fruit contains large amounts of the toxic alkaloid solanine, and is therefore unsuitable for consumption.
All new potato varieties are grown from seeds, also called "true seed" or "botanical seed" to distinguish it from seed tubers. By finely chopping the fruit and soaking it in water, the seeds will separate from the flesh by sinking to the bottom after about a day (the remnants of the fruit will float). Any potato variety can also be propagated vegetatively by planting tubers, pieces of tubers, cut to include at least one or two eyes, or also by cuttings, a practice used in greenhouses for the production of healthy seed tubers. Some commercial potato varieties do not produce seeds at all (they bear imperfect flowers) and are propagated only from tuber pieces. Confusingly, these tubers or tuber pieces are called "seed potatoes".
Botanists are in general agreement that potato species originated in the Andes, from Colombia and Venezuela to Chile and northern Argentina, but genetic diversity, both in wild and cultivated species, is concentrated in the area of Peru. According to a series of genetic studies, experts consider that the potato Solanum brevicaule, located in Peru's portion of the Titicaca, is the single ancestor of all potatoes in the world as it originiated more than 10,000 years ago. The first European description of the potato was in Pedro Cieza de León's Crónica del Perú (Seville 1533). Around the same time, the potato was introduced into cultivation in Spain under its Quechua name, papa. A notice of 1573 shows that potatoes were being fed to the sick in a monastery of Seville, still under their Quechua name.
Outside Spain, the potato was a botanical curiosity, which knowledgeable people considered poisonous due to its relation to Deadly Nightshade. It was introduced in France about 1540 and cultivated at Saint-Alban-d'Ay under the name truffole. It first appeared in botanical literature in Gaspard Bauhin's Pinax Theatri Botanici, 1596. Olivier de Serres described the cartoufle in 1600, declaring "This plant called cartoufle carries fruits of the same name, similar to truffles.
The Andean variety Solanum tuberosum ssp. andigena was the first introduced to Europe and dominated European production until a few decades before the Irish Potato Famine, according to recently published DNA analysis. The same research shows that in the early 19th century, the Chilean Solanum tuberosum ssp. tuberosum, adapted to long-day growing conditions, was introduced to Europe. It quickly replaced the Andean short-day variety.
By mid 18th century the potato was grown and eaten in northern Italy, Spain, Germany, Poland. Popular history credits Sir Walter Raleigh with its introduction to Great Britain and Ireland, although one of his men, Thomas Harriott, is also credited. But in France it was considered merely animal feed. Its introduction to the French kitchen is legitimately credited to Antoine Parmentier, who had been forcibly introduced to it during a period of military captivity in Prussia during the Seven Years' War. After local shortages in 1769, the Academy of Besançon conducted a competition in 1771 on the theme of vegetables that could supplement those commonly in use during years of want, and what would be their preparation. Parmentier won first prize, among several who were recommending the potato. His stratagem for introducing it among French peasants has become legend; he had a field of potatoes grown near Paris watched (lightly) by royal troops, as if it were a delicacy fit only for nobles' tables. The local peasantry managed to steal samples and the potato was launched in French cuisine, where potato dishes are still styled "à la Parmentier".
Historical and genetic evidence suggests that the potato reached India soon after Europe, taken by either the British or the Portuguese. Genetic studies show that all 32 varieties of potato grown in India derive from the Chilean subspecies. The earliest unequivocal reference to the potato in India is in an 1847 British journal.
There are two major subspecies of Solanum tuberosum: andigena, or Andean; and tuberosum, or Chilean. The Andean potato is adapted to the short-day conditions prevalent in the mountainous equatorial and tropical regions where it originated. The Chilean potato is adapted to the long-day conditions prevalent in the higher latitude region of southern Chile, especially on Chiloé Island where it is thought to have originated.
There are about five thousand potato varieties world wide. Three thousand of them are found in the Andes alone, mainly in Peru, Bolivia, Ecuador, Chile and Colombia. They belong to eight or nine species, depending on the taxonomic school. Apart from the five thousand cultivated varieties, there are about 200 wild species and subspecies, many of which can be cross-bred with cultivated varieties, which has been done repeatedly to transfer resistances to certain pests and diseases from the gene pool of wild species to the gene pool of cultivated potato species.
Most modern potatoes grown in North America arrived through European settlement and not independently from the South American sources. However, at least one wild potato species, Solanum fendleri, is found as far north as Texas and used in breeding for resistance to a nematode species attacking cultivated potatoes. A secondary center of genetic variability of the potato is Mexico, where important wild species are found that have been used extensively in modern breeding, such as the hexaploid Solanum demissum, as a source of resistance to the devastating late blight disease. Another plant native to this region, Solanum bulbocastanum, a close relative of the potato, has been used to genetically engineer the potato to effectively resist potato blight.
The potato became an important staple crop in northern Europe as the climate changed due to the Little Ice Age, when traditional crops in this region did not produce as reliably as before. At times when and where most other crops would fail, potatoes could still typically be relied upon to contribute adequately to food supplies during the colder years. The potato was not popular in France during this time, and it is believed that some of the infamous famines could have been lessened if French farmers had adopted it. Today, the potato forms an important part of the traditional cuisines of most of Europe. Belarus has the highest consumption of potato per capita with each Belorussian consuming 338 kg in 2005.
Nutritionally, potatoes are best known for their carbohydrate content (approximately 26 grams in a medium potato). The predominant form of this carbohydrate is starch. A small but significant portion of this starch is resistant to digestion by enzymes in the stomach and small intestine, and so reaches the large intestine essentially intact. This resistant starch is considered to have similar physiological effects and health benefits as fiber: it provides bulk, offers protection against colon cancer, improves glucose tolerance and insulin sensitivity, lowers plasma cholesterol and triglyceride concentrations, increases satiety, and possibly even reduces fat storage (Cummings et al. 1996; Hylla et al 1998; Raban et al. 1994). The amount of resistant starch in potatoes depends much on preparation methods. Cooking and then cooling potatoes significantly increases resistant starch. For example, cooked potato starch contains about 7% resistant starch, which increases to about 13% upon cooling (Englyst et al. 1992).
Potatoes contain a number of important vitamins and minerals. A medium potato (150g/5.3 oz) with the skin provides 27 mg vitamin C (45% of the Daily Value (DV)), 620 mg of potassium (18% of DV), 0.2 mg vitamin B6 (10% of DV) and trace amounts of thiamin, riboflavin, folate, niacin, magnesium, phosphorus, iron, and zinc. Moreover, the fiber content of a potato with skin (2 grams) equals that of many whole grain breads, pastas, and cereals. Potatoes also contain an assortment of phytochemicals, such as carotenoids and polyphenols. The notion that “all of the potato’s nutrients” are found in the skin is an urban legend. While the skin does contain approximately half of the total dietary fiber, more than 50% of the nutrients are found within the potato itself. The cooking method used can significantly impact the nutrient availability of the potato.
Potatoes are often broadly classified as high on the glycemic index (GI) and so are often excluded from the diets of individuals trying to follow a “low GI” eating regimen. In fact, the GI of potatoes can vary considerably depending on type (such as red, russet, white, or Prince Edward), origin (where it was grown), preparation methods (i.e., cooking method, whether it is eaten hot or cold, whether it is mashed or cubed or consumed whole, etc), and with what it is consumed (i.e., the addition of various high fat or high protein toppings) (Fernandes et al. 2006).
Potatoes are prepared in many ways: skin-on or peeled, whole or cut up, with seasonings or without. The only requirement involves cooking to break down the starch. Most potato dishes are served hot, but some are first cooked then served cold, notably potato salad and potato chips/crisps.
Common dishes are: mashed potatoes, which are first boiled (usually peeled), and then mashed with milk or yogurt and butter; whole baked potatoes; boiled or steamed potatoes; French-fried potatoes or chips; cut into cubes and roasted; scalloped, diced, or sliced and fried (home fries); grated into small thin strips and fried (hash browns); grated and formed into dumplings, Rösti or potato pancakes. Unlike many foods, potatoes can also be easily cooked in a microwave oven and still retain nearly all of their nutritional value, provided that they are covered in ventilated plastic wrap to prevent moisture from escaping—this method produces a meal very similar to a steamed potato while retaining the appearance of a conventionally baked potato. Potato chunks also commonly appear as a stew ingredient.
Potatoes are boiled between 10 and 25 minutes, depending on size and type, to become soft.
In Ecuador the potato, as well as being a staple with most dishes, is featured in the hearty Locro de Papas, a thick soup of potato, squash, and cheese.
In Chile's Chiloé archipelago, potatoes are the main ingredient of many dishes, including milcaos, chapaleles, curanto and chochoca.
In Ireland Colcannon is a traditional Irish dish involving mashed potato combined with shredded cabbage and onion. Boxty pancakes are eaten all over Ireland, although associated especially with the north, and in Irish diaspora communities: they are traditionally made with grated potatoes, soaked to loosen the starch and mixed with flour, buttermilk and baking powder. A variant eaten and sold in Lancashire, especially Liverpool, is made with cooked and mashed potatoes.
In Northern and Eastern Europe, especially in Scandinavian countries, Poland, Russia, Belarus and Ukraine, newly harvested, early ripening varieties are considered a special delicacy. Boiled whole and served with dill, these "new potatoes" are traditionally consumed together with Baltic herring.
In Western Europe, especially in Belgium, sliced potatoes are fried to get frieten, the original French fried potatoes. Stamppot, a traditional Dutch meal, is based on mashed potatoes mixed with vegetables.
Potatoes are very popular in continental Europe as well. In Italy, they serve to make a type of pasta called gnocchi. Similarly, cooked and mashed potatoes or potato flour can be used in the knödel or dumpling eaten with or added to meat dishes all over central and Eastern Europe, but especially in Bavaria and Luxembourg. Potatoes form one of the main ingredients in many soups such as the pseudo-French vichyssoise and Albanian potato and cabbage soup. In western Norway, komle is popular.
A traditional Canary Islands dish is Canarian wrinkly potatoes or Papas arrugadas. Tortilla de patatas (potato omelete) and Patatas bravas (a dish of fried potatoes in a spicy tomato sauce) are near-universal constituent of Spanish tapas.
In the United States, potatoes have become one of the most widely consumed crops and thus have a variety of preparation methods and condiments. French fries and often hash browns are commonly found in typical American fast-food burger joints and cafeterias. One popular favorite involves a baked potato with cheddar cheese (or sour cream and chives) on top, and in New England "smashed potatoes" (a chunkier variation on mashed potatoes, retaining the peel) have great popularity. Potato flakes are popular as an instant variety of mashed potatoes, which reconstitute into mashed potatoes by adding water, plus butter & salt for taste. A regional dish of Central New York, salt potatoes are bite-sized new potatoes boiled in water saturated with salt then served with melted butter. At more formal dinners, a common practice includes taking small red potatoes, slicing them, and roasting them in an iron skillet. Among American Jews, the practice of eating latkes (fried potato pancakes) is common each winter, when Hannukah comes.
A traditional Acadian dish from New Brunswick is known as poutine râpée. The Acadian poutine is a ball of grated and mashed potato, salted, sometimes filled with pork in the center, and boiled. The result is a moist ball about the size of a baseball. It is commonly eaten with salt and pepper or brown sugar. It is believed to have originated from the German Klöße, prepared by early German settlers who lived among the Acadians.
Poutine, by contrast, is a hearty serving of french fries, fresh cheese curds and hot gravy. Tracing its origins to Quebec in the 1950s, it has become popular across Canada and can usually be found where Canadians gather abroad.
Potatoes contain glycoalkaloids, toxic compounds, of which the most prevalent are solanine and chaconine. Cooking at high temperatures (over 170 °C or 340 °F) partly destroys these. The concentration of glycoalkaloid in wild potatoes suffices to produce toxic effects in humans. Glycoalkaloids occur in the greatest concentrations just underneath the skin of the tuber, and they increase with age and exposure to light. Glycoalkaloids may cause headaches, diarrhea, cramps and in severe cases coma and death; however, poisoning from potatoes occurs very rarely. Light exposure also causes greening, thus giving a visual clue as to areas of the tuber that may have become more toxic; however, this does not provide a definitive guide, as greening and glycoalkaloid accumulation can occur independently of each other. Some varieties of potato contain greater glycoalkaloid concentrations than others; breeders developing new varieties test for this, and sometimes have to discard an otherwise promising cultivar.
Breeders try to keep solanine levels below 200 mg/kg (200 ppmw). However, when these commercial varieties turn green, even they can approach concentrations of solanine of 1000 mg/kg (1000 ppmw). In normal potatoes, analysis has shown solanine levels may be as little as 3.5% of the breeders' maximum, with 7–187 mg/kg being found.
The US National Toxicology Program suggests that the average American consumes at most 12.5 mg/day of solanine from potatoes (the toxic dose is actually several times this, depending on body weight). Dr. Douglas L. Holt, the State Extension Specialist for Food Safety at the University of Missouri, notes that no reported cases of potato-source solanine poisoning have occurred in the U.S. in the last 50 years and most cases involved eating green potatoes or drinking potato-leaf tea.
Solanine is also found in other plants, mainly in the mostly deadly nightshade family, which includes a minority of edible plants including the potato and the tomato, and other typically more dangerous plants like tobacco. This poison affects the nervous system causing weakness and confusion.
Correct potato husbandry is an arduous task in the best of circumstances. Good ground preparation, harrowing, plowing, and rolling are always needed, along with a little grace from the weather and a good source of water. Three successive plowings, with associated harrowing and rolling, are desirable before planting. Eliminating all root-weeds is desirable in potato cultivation. Potatoes are the most fruitful of the root crops, but much care and consideration is needed to keep them satisfied and fruitful.
Potatoes are generally grown from the eyes of another potato and not from seed. Home gardeners often plant a piece of potato with two or three eyes in a hill of mounded soil. Commercial growers plant potatoes as a row crop using seed tubers, young plants or microtubers and may mound the entire row.
Seed potato crops are 'rogued' in some countries to eliminate diseased plants or those of a different variety from the seed crop.
Potatoes should be harvested before heavy frosts, which damage potatoes in the ground, and even cold weather makes potatoes more susceptible to bruising and possibly later rotting which can quickly ruin a large stored crop.
At harvest time, gardeners usually dig up potatoes with a long-handled, three-prong "grape" (or graip), i.e. a spading fork, or a potato hook which is similar to the graip but its tines are at a 90 degree angle to the handle. In larger plots, the plow can serve as the fastest implement for unearthing potatoes. Commercial harvesting is typically done with large potato harvesters which scoop up the plant and the surrounding earth. This is transported up an apron chain consisting of steel links several feet wide, which separates some of the dirt. The chain deposits into an area where further separation occurs. Different designs use different systems at this point. The most complex designs use vine choppers and shakers, along with a blower system or "Flying Willard" to separate the potatoes from the plant. The result is then usually run past workers who continue to sort out plant material, stones, and rotten potatoes before the potatoes are continuously delivered to a wagon or truck. Further inspection and separation occurs when the potatoes are unloaded from the field vehicles and put into storage.
Potatoes are usually cured after harvest to thicken their skin. Prior to curing, the skin is very thin and delicate. These potatoes are sometimes sold as "New Potatoes" and are particularly flavorful. New potatoes are often harvested by the home gardener or farmer by "grabbling", i.e. pulling out the young tubers by hand while leaving the plant in place. In additions, markets may sometimes present various thin-skinned potato varieties as "new potatoes".
Storage facilities need to be carefully designed to keep the potatoes alive and slow the natural process of decomposition, which involves the breakdown of starch. It is crucial that the storage area is dark, well ventilated and for long-term storage maintained at temperatures near 40°F (4°C). For short-term storage prior to cooking, temperatures of about 45-50°F (7-10°C) are preferred. Temperatures below 40°F (4°C) convert potatoes' starch into sugar, which alters their taste and cooking qualities and leads to higher acrylamide levels in the cooked product, especially in deep-fried dishes.
Under optimum conditions possible in commercial warehouses, potatoes can be stored for up to six months, at homes usually only for several weeks. If potatoes develop green areas or start to sprout, these areas should be trimmed before using.
FAO reports that the world production of potatoes in 2006 was 315 million tonnes. The largest producer, China, accounted for one-fourth of the global output, followed by Russia and India.
In recognition of this importance, the United Nations officially declared the year 2008 as the International Year of the Potato in order to “increase awareness of the importance of the potato as a food in developing nations” and calling the vegetable a “hidden treasure”. This follows the International Rice Year in 2004.
Genetic research has produced at least one genetically modified variety, the New Leaf, owned by Monsanto corporation. On September 22, 2007, Benguet State University (BSU) announced that four potato varieties—Igorota, Solibao, Ganza and one not yet officially named—possess more than 18% dry matter content required by fast-food chains to make crispy and sturdy French fries.
Some horticulturists sell chimeras, made by grafting a tomato plant onto a potato plant, producing both edible tomatoes and potatoes. This practice is not very widespread.
A major disease of potato plants is potato blight caused by Phytophthora infestans.
The potato has been an essential crop in the Andes since the pre-Columbian Era. The Moche culture from Northern Peru made ceramics from earth, water, and fire. This pottery was a sacred substance, formed in significant shapes and used to represent important themes. Potatoes are represented anthropomorphically as well as naturally.