The potato is one of the main food crops of the world. It may have originated in South America. The potato plant is related to the tomato and the tobacco plants but not to the plant known as the sweet potato.

Physical characteristics

The potato plant is an herb. An herb is a plant without a woody stem. The potato plant bears white or purplish flowers. Each potato leaf is divided into leaflets. Such a leaf is known as a compound leaf. The compound potato leaf is about 8 to 12 inches (20 to 30 centimeters) long.

The stem of the potato plant grows underground. It extends into structures called stolons. The stolons may enlarge greatly at the tips, thereby forming from a few to more than 20 tubers of varied shapes and sizes. The tubers are the parts of the potato plant that can be eaten. The plant's leaves manufacture the starch that is stored in the potato's tubers.

The skin of the potato tuber varies in color from brownish white to deep purple. Its flesh normally ranges in color from white to yellow, but it also may be purple.

Varieties

The potatoes cultivated in South America as early as 1,800 years ago probably included a mixture of varieties. Today more than 500 varieties of potato are grown. Commercial potato varieties can be classified by their appearance into four groups: rough white, russet (mostly long), round red, and long white.

Life cycle

Potatoes grow well in cool climates, in a light sandy or clay loam soil. The plant is not commonly grown from seed but rather from pieces of the tuber. Each potato tuber bears buds, also known as eyes. When the conditions are right, these buds grow into new plants. The new plants are identical to the plant that bore the tubers. Commercial varieties of potato are grown from tuber buds. In this way a potato plant of a select variety will give rise to other plants of the same variety.

Diseases

Potato plants have many natural enemies. One very destructive enemy is the Colorado potato beetle, more commonly called the potato bug. It feeds on the leaves of the plant.

The potato leafhopper is another destructive insect. It sucks up juices from the plant. The insect's saliva causes thickening of the cells of the potato leaf. As a result, the vessels that transport food through the plant can no longer do their work. The leaves turn brown, curl, and die. This injury, called “hopper burn,” can result in complete loss of a potato crop if not controlled.

A louse known as a psyllid feeds on potato leaves and causes curling and yellowing of leaves. The condition is known as “potato yellows.” Small organisms known as fungi cause diseases such as early blight, rot, late blight, scab, and wilt.

Uses

The potato tuber has been important in cooking for a very long time. They contain many vitamins and minerals. The most common ways of cooking potatoes are boiling, frying, and baking. Potatoes are frequently served whole, mashed as a cooked vegetable, or cut up as French fries. They are also made into potato chips, flour, starch, and alcoholic drinks. Potato starch has many industrial uses. It is used as a thickener in foods and provides tough coatings for paper and textiles.

History

The Spanish conquerors who reached the Andes Mountains in Peru in the early 1500s learned about potatoes from the Inca people. The Spaniards called them batata because they resembled the sweet potato grown in the West Indies. The English changed the name to potato.

It is not precisely known who took the first potatoes to Europe. It seems certain that potatoes had reached Spain by about 1570, however. Europeans did not know their food value. For a long time potatoes were grown only as an interesting plant. They were shipped from England to Bermuda in 1613 and from there to North America.

By the end of the 17th century potatoes had become the staple food of the Irish. The French scientist Antoine-Augustin Parmentier helped quiet the fears of French peasants, who thought that potatoes caused fevers and the disease leprosy. Between 1773 and 1789 he wrote books and pamphlets urging potato cultivation. King Louis XVI of France popularized the potato by wearing potato flowers in his buttonhole. Frederick the Great of Prussia ordered his subjects to plant potatoes as food and cattle feed. By the end of the 18th century potatoes were a major crop in Europe, particularly in Germany and in the west of England.

The Irish economy became dependent upon the potato. In the mid-19th century a disease called late blight reached Ireland from North America. Late blight destroys potato leaves and tubers. For years much of the country's potato crop rotted in the fields. A major famine resulted. More than a million people died from starvation or famine-related diseases.