Potato

Potato, edible starchy tuber. It is produced by certain plants of the nightshade family, especially the common white potato. The name is also applied to the plants. The white-potato tuber is a food staple in most countries of the temperate regions of the world. The plant is grown as an annual herb. The stem attains a length of up to almost 1 m (almost 3 ft), erect or prostrate, with pointed leaves and white to purple flowers. The fruit is a many-seeded berry about the size of a cherry. Like the stems and the foliage, the fruit contains significant amounts of solanin, a poisonous alkaloid characteristic of the genus.

The plant, native to the Peruvian Andes, was brought to Europe in the 16th century by Spanish explorers. The cultivation of the potato spread rapidly, especially in the temperate regions, and early in the 18th century the plant was introduced into North America. The earliest authentic record of its cultivation there was dated 1719, at Londonderry, New Hampshire. In the United States, the majority of potatoes are grown in Idaho and Washington. The early crop is produced by California and the Gulf states; as the season advances, the harvest moves to the states of the Great Plains, the Pacific Northwest, and the Northeast. (See also Crop Farming.)

In ordinary cultivation, propagation is accomplished by planting the tuber or a section of the tuber containing an eye, which is an undeveloped bud. New varieties are developed from seed produced after controlled pollination. Improved varieties may be propagated rapidly by using cuttings from the sprouts. Rich, sandy loams are most suitable for producing the light, mealy types favored by American and British taste; heavy, moist soils produce the firm type preferred by Europeans. Named varieties popular in the United States include Rose, Idaho, Cobbler, Early Ohio, Green Mountain, Hebron, Rural, and Burbank.

Freshly dug potatoes contain 78 percent water, 18 percent starch, 2.2 percent protein, 1 percent ash (inorganic material), and 0.1 percent fat. About 75 percent of the dry weight is carbohydrate. The potato is an important source of starch for the manufacture of adhesives and alcohol.

The most important disease of the potato is late blight, caused by a fungus-like organism that rots leaves, stems, and tubers, and which was responsible for the Irish Potato Famine between 1845 and 1850. The early blight, caused by a true fungus, is not so destructive but causes lesions that permit entry of the various forms of bacterial rot. Several forms of mosaic disease and leaf curl are caused by infection with viruses. The Colorado potato beetle is the most destructive of the insect pests; others include the potato leafhopper, the potato flea beetle, and species of aphids and psyllids. See also Sweet Potato.

Scientific classification: Potatoes are produced by plants that belong to the family Solanaceae. The common white potato is classified as Solanum tuberosum.