Potato

Scientific classification

Kingdom: Plantae

(unranked): Angiosperms

(unranked): Eudicots

(unranked): Asterids

Order: Solanales

Family: Solanaceae

Genus: Solanum

Species: S. tuberosum

Binomial name

Solanum tuberosum L.

The potato is a starchy, tuberous crop from the perennial Solanum tuberosum of the Solanaceae family (also known as the nightshades). The word potato may refer to the plant itself as well. In the region of the Andes, there are some other closely related cultivated potato species. Potatoes are the world's fourth largest food crop, following rice, wheat, and maize. Long term storage of potatoes requires specialised care in cold warehouses and such warehouses are among the oldest and largest storage facilities for perishable goods in the world.

Wild potato species occur from the United States to Uruguay and Peru. 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, from a species in the Solanum brevicaule complex. Although Peru is essentially the birthplace of the potato, today over 99% of all cultivated potatoes 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 ssp. tuberosum, is believed to be indigenous to the Chiloé Archipelago where it was cultivated as long as 10,000 years ago.

Introduced to Europe in 1536, the potato was subsequently conveyed by European mariners to territories and ports throughout the world. Thousands of varieties persist in the Andes, where over 100 cultivars 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 oomycete Phytophthora infestans, spread rapidly through the poorer communities of western Ireland, resulting in the crop failures that led to the Great Irish Famine. The potato was the first vegetable inherited by the early Australians, the Aborigines.

The annual diet of an average global citizen in the first decade of the twenty-first century would include about 33 kg (or 73 lb) of potato. However, the local importance of potato is extremely variable and rapidly changing. It 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 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, although the degree of this trend is ambiguous.

   Potato plants are herbaceous perennials that grow about 60 cm (24 in) high, depending on variety, the culms dying back after flowering. They bear white, pink, red, blue or purple flowers with yellow stamens. The tubers of varieties with white flowers generally have white skins, while those of varieties with colored flowers tend to have pinkish skins. 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. Tubers form in response to decreasing day length, although this tendency has been minimized in commercial varieties.

Potato plantsAfter 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 greenhouse