The potato (Solanum tuberosum) is a perennial plant of the Solanaceae, or nightshade, family, grown for its starchy tuber. Potatoes form the world's most important non-cereal crop, and grow world-wide. Growers cultivate thousands of different varieties of potato.
The potato has only a very distant relationship with the sweet potato. In areas of the United States where sweet potatoes are common, people sometimes refer to the "Irish potato" to distinguish the two, a reference to the widespread cultivation of potatoes in Ireland in the 19th century.
Naming of the potato
In the 16th century, the Spaniards introduced potatoes to Europe. The name "potato" came from the Spanish word "patata" (the original Quechua word appears as "papa"). Many other European languages took forms of this Spanish name, but popular alternatives exist in English, such as spuds, murphies, taters, or taties. In the Americas, Spanish-speakers use the word "papa" more commonly than "patata". Interestingly, French-speakers call the potato pomme de terre meaning literally "apple of earth".
Scientists believe that the potato plant originally came from the Andes. Pre-Columbian societies of this region (pre-cursors of the Inca civilization) cultivated it originally, and it spread over time to other Native American groups and became a staple food in some areas.
Popular legend has long credited Sir Walter Raleigh with first bringing the potato to England, but history suggests Sir Francis Drake as a more likely candidate. In 1586, after battling the Spaniards in the Caribbean, Drake stopped at Cartagena in Colombia to collect provisions including tobacco and potato tubers. Before returning to England he stopped at Roanoke Island, where the first English settlers had attempted to set up a colony. The pioneers returned to England with Drake, along with the potatoes.
Agriculturalists soon found potatoes easier to grow and cultivate than other staple crops, such as wheat and oats; potatoes produce more food energy than any other European crop for the same area of land and require only a shovel for harvesting. For all these reasons potatoes became, by 1650, the staple food of Ireland, and they began to replace wheat as the major crop elsewhere in Europe, being used to feed both people and animals. The first mention of potatoes appearing in North America comes from Irish settlers in Londonderry, New Hampshire during 1719. By the end of the 18th Century the potato had become popular in France, due to the advocacy of Antoine Augustine Parmentier, an employee of King Louis XV.
The potato became such an important food for the Irish that the popular imagination automatically associates it with them today, but its early history in Ireland remains obscure. One speculation has it that the potato may have originally arrived in Ireland washed ashore from wrecked galleons of the Spanish Armada (1588). Another story credits the introduction of the potato in Ireland to Sir Walter Raleigh, who did finance transatlantic expeditions, at least one of which made landfall at Smerwick, County Kerry in October, 1587, but no record survives of what botanical specimens it may have carried or whether they thrived in Ireland. Some stories say that Sir Walter first planted the potato on his estate near Cork. A 1699 source (over one century after the event) says 'The potato .... Was brought first out of Virginia by Sir Walter Raleigh, and he stopping at Ireland, some was planted there, where it thrived well and to good purpose, for in three succeeding wars, when all the corn above ground was destroyed, this supported them; for the soldiers, unless they had dug up all the ground where they grew, and almost sifted it, could not extirpate them.'  (http://www.finnvalley.ie/irelandsown/spuds/potato.html).
Whatever the source, the potato became popular in Ireland both because of its high productivity and because of the ability to easily hide it underground. English landlords also encouraged potato-growing by Irish tenants because they wanted to produce more wheat if the Irish could survive on a crop that took less land, that would free a greater area for wheat production.
A single devastating event however, looms large in the Irish history of potatoes the Irish potato famine. In the 1840s a major outbreak of potato blight swept through Europe, wiping out the potato crop in many countries. The Irish economy dependended so heavily on a single variety of potatoes the unpalatable but fertile 'lumper' that the famine led to almost a million deaths, and the subsequent emigration of millions more Irish (see Irish diaspora).
By the seventeenth century the potato had become firmly established as a staple of Europe's poor, leading richer people to spurn it, although this changed gradually, with Antoine-Auguste Parmentier's persuading King Louis XVI of France of the value of the crop. The soup potage Parmentier takes its name from the great horticulturalist.
In Russia, potatoes met with initial suspicion: the people called them "the Devil's apples" because of folklore surrounding things which grow underground or which have associations with dirt.
Potatoes' skins come in the colors brown, yellow, pink, red, and purple (sometimes called "blue"). Their flesh may appear white or may reflect the color of the skin. The market calls small types "fingerlings" or "new" potatoes, larger potatoes may class as "earlies" or "main crop", with the "main crop" referring to varieties that will store well. Individual varieties may be labeled "boiling", indicating that they retain some shape when boiled, "baking", indicating that they only hold their shape if baked, "roasting", indicating that they are flavoursome when roasted, "salad" to indicate suitability for salad use (often firm and waxy fleshed when boiled), or "mashing" to indicate that when mashed they form a smooth consistency, neither fibrous nor grainy.
Common North American potato varieties include:
- Burbank Russet large, brown skin, white-fleshed, developed by Luther Burbank
- Yellow Finn small, with yellow skin and flesh
- Red Gold red skin, yellow flesh
- German Butterball a yellow fleshed small oval potato. Won first place in Rodale's Organic Gardening "Taste Off"
- Yukon Gold yellow skin and flesh
In the United States the term "Idaho potato" is often used, but does not denote a variety, but simply an origin in Idaho, that country's principal potato-growing region.
Common British potato varieties include:
- Maris Piper a good general purpose white main crop potato, not suitable for salads. The favourite potato of chip shops
- King Edward the best roasting potato, often served with the Sunday roast, white main crop
- Desiree a red skinned main crop potato, a favourite with allotment holders because of disease resistance
- International Kidney trademarked as Jersey Royal, a salad new potato, grown on the island of Jersey and in Spain
- Pink Fir Apple a pink-skinned salad potato which grows in irregular shapes
- Golden Wonder famous Scottish frying potato used to make the eponymous crisps
- Kerrs Pinks: bred in Northern Ireland: an excellent potato for boiling.
Common French varieties include
- Amandine is a variety of early potato, descended from the varieties Charlotte and Mariana. It was bred in Brittany, France and entered in the national list of potato varieties in 1994. Amandine potatoes are typically long, with very pale, unblemished skin. Their flesh is firm and also very pale, and contains comparatively little starch. Amandine potatoes have become popular in Switzerland.
Countries such as Peru, the native area of origin for potatoes, can offer a much wider range of varieties.
Potatoes have a high carbohydrate content and include protein, minerals (particularly potassium, calcium), and vitamins, including vitamin C. Freshly harvested potatoes retain more vitamin C than stored potatoes.
A benefit of new and fingerling potatoes is that they contain less toxic chemicals. Such potatoes are an excellent source of nutrition. Peeled, long-stored potatoes have less nutritional value, especially when fried, although they still have potassium and vitamin C.
Cooks and chefs can prepare potatoes for eating in numerous ways: either with their skin on or peeled, whole or cut into pieces, and with seasonings or without. The only requirement involves cooking to break down the starch and make them edible. Most end-consumers eat potatoes hot, but several basic potato recipes involve cooking the potatoes and then eating them cold potato salad and potato crisps (called "potato chips" in some places, such as the U.S.). One of the most common presentation methods involves mashing potatoes: peeling, boiling, then mashing and mixing with butter, cream, or other seasonings before serving. Mashed potatoes form a major component of several traditional dishes from the British Isles such as shepherd's pie, bubble and squeak, and the 'tatties' which accompany haggis.
Other presentations or dishes may see potatoes baked whole; boiled; steamed; cut into cubes and roasted; diced or sliced and fried (home fries); grated into small thin strips and fried (hash browns); grated and formed into dumplings, Rφsti or potato pancakes; and cut into long, thin pieces and fried or baked (chips, traditionally called "French fries" in the U.S.). Potatoes also serve to make a type of pasta called gnocchi. Potatoes form one of the main ingredients in many soups such as the pseudo-French vichyssoise and Albanian potato and cabbage soup. Potato chunks also commonly appear as a stew ingredient.
Toxic compounds in potatoes
Potatoes contain glycoalkaloids, toxic compounds, of which the most prevalent are solanine and chaconine. Cooking at high temperatures (over 170 degrees C) partly destroys these. 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 0.2 mg/g (200 ppm). However, when even these commercial varieties turn green, they can approach concentrations of solanine of 1 mg/g (1000 ppm). Some studies suggest that 200 mg of solanine can constitute a dangerous dose. This dose would require eating 1 average-sized spoiled potato or 4 to 9 good potatoes (over 3 pounds) at one time. The National Toxicology Program suggests that the average American consumes 12.5 mg/person/day of solanine from potatoes. Dr. Douglas L. Holt, the State Extension Specialist for Food Safety at the University of Missouri - Columbia, 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.
Potato plants have a low-growing habit and bear white flowers with yellow stamens. They grow best in cool climates with good rainfall or irrigation such as Maine, Idaho, New Brunswick, Prince Edward Island, Belarus, Germany, Poland, and Russia. But they adapt readily, and producers grow them, at least on a small scale, in most temperate regions.
Buds called "eyes" appear on the surface of potato tubers. Since common varieties of potatoes do not produce seeds (they bear sterile flowers) propagation occurs by planting pieces of existing tubers, cut to include at least one eye. Confusingly, these pieces can bear the name "seed potatoes".
Practical tips originally from the 1881 Household Cyclopedia
To reduce the ground till it is completely free from root-weeds, may be considered as a desideratum in potato husbandry; though in many seasons these operations cannot be perfectly executed, without losing the proper time for planting, which never ought to come after the first of May, if circumstances do not absolutely interdict it. Three ploughings, with frequent harrowings and rollings, are necessary in most cases before the land is in suitable condition. When this is accomplished form the drills as if they were for turnips; cart the manure, which ought not to be sparingly applied, plant the seed above the manure, reverse the drills for covering it and the seed, then harrow the drills in length, which completes the preparation and seed process.
Cutting the seed into small slips does not provide any advantage, for the strength of the stem at the outset depends in direct proportion upon the vigor and power of the seed-plant. The seed plant, therefore, ought to be large, rarely smaller than the fourth-part of the potato; and if the seed is of small size, one-half of the potato may be profitably used. At all events, rather err in giving over large seed than in making it too small because, by the first error, no great loss can ever be sustained; whereas, by the other, feeble and late crop may be the consequence. When the seed is properly cut, it requires from ten to twelve hundredweight of potatoes to plant an acre (1.2 to 1.5 t/ha) of ground, where the rows are twenty seven inches (700 mm) apart; but this quantity depends greatly upon the size of the potatoes used; large potatoes may require a greater weight, but the extra quantity will be abundantly repaid by the superiority of crop which large seed usually produces.
Cultivation should go twelve inches deep, if the soil will allow it; after this, the gardener should open a hole (about six inches (150 mm) deep and not more than twelve inches (300 mm) in diameter) and place horse-dung or long litter therein, about three inches (75 mm) thick. Upon this dung or litter plant a potato whole, shake a little more dung over it, and then cover with earth. In like manner the whole plot of ground must be planted, taking care that the potatoes be at least sixteen inches apart. When the young shoots make their appearance they should have fresh mould drawn around them with a hoe; and if the tender shoots are covered, it will prevent the frost from injuring them; they should again be earthed when the shoots make a second appearance, but not covered, as in all probability the season will be less severe.
Provide a plentiful supply of mould, taking care never to tread upon the plant, or upon the hillock raised round it, as the looser the earth the more room the potato will have to expand.
A gentleman obtained from a single root, thus planted, very nearly forty pounds weight of large potatoes, and from almost every other root upon the same plot of ground from fifteen to twenty pounds weight; and, unless in stony or gravelly soil, ten pounds or half a peck of potatoes may generally be obtained from each root by pursuing the foregoing method.
But note: cuttings or small sets will not do for this purpose.
Potatoes are generally dug up with a three-prong grape or fork, but at other times, when the weather is dry, the plough is used, which is the most expeditious implement. After gathering the interval, the furrow taken by the plough is broken and separated, in which way the crop may be more completely gathered than when taken up by the grape. The potatoes are then stored up for winter and spring use; and as it is of importance to keep them as long through summer as possible, every endeavor ought to be made to preserve them from frost, and from sprouting in the spring months. The former is accomplished by covering them well with straw when lodged in a house, and by a thick coat of earth when deposited in a pit, and the latter, by picking them carefully at different times, when they begin to sprout, drying them sufficiently by exposure to the sun, or by a gentle toast of a kiln.
Lord Farnham, in a letter to Sir John Sinclair, particularly recommends the drill system in the cultivation of potatoes in Ireland. The small farmers and laborers plant them in lazy-beds, eight feet wide. They do so on account of the want of necessary implements for practising the drill system, together with a want of horses for the same purpose.
They are cut into sets, three from a large potato; and each set to contain at least one eye. The sets are planted at the distance of seven inches asunder, six and a quarter hundredweight are considered sufficient seed for a British acre. Lord Farnham recommends rotten dung in preference to any fresh dung. If not to be procured, horse-dung, hot from the dunghill. In any soil he would recommend the dung below the seed.
When the potatoes are vegetated ten inches above the surface, the scuffler must be introduced, and cast the mold from the potato. Hand-hoe any weeds found in the drills; in three days afterwards they must be moulded up by the double-breasted plough, as high as the neck of the potato. This mode must be practiced twice, or in some cases three times, particularly if the land is foul. I do not (says Lord Farnham) consider any mode so good as the drill system.
To prepare for the drill system either oat or wheat stubble, plough in October or at the beginning of November; to be ploughed deep and laid up for winter dry. In March let it be harrowed, and give it three clean earths. Be very particular to eradicate the couch grass. The drills to be three feet asunder; drill deep the first time that there is room in the bottom of the furrow to contain the dung. The best time to begin planting the potatoes is about the latter end of April by this system. It is as good a preparation for wheat as the best fallows.
Three feet and a half for drills are preferable to four feet. Mr. Curwen prefers four feet and a half. He says the produce is immense. Potatoes ought to be cut at least from two to three weeks before being planted; and if planted very early whole potatoes are preferable to cut ones, and dung under and over. Some agriculturists lately pay much attention to raising seedling potatoes, with the hope of renewing the vigor of the plant.
One can produce early potatoes in great quantity by resetting the plants, after taking off the ripe and large ones. A gentleman at Dumfries has replanted them six different times in one season, without any additional manure; and, instead of falling off in quantity, he gets a larger crop of ripe ones at every raising than the former ones. His plants have still on them three distinct crops, and he supposes they may still continue to vegetate and germinate until the frost stops them. By this means he has a new crop every eight days, and has had so for a length of times.