The edible seeds of various leguminous plants are commonly called beans. The species that has probably been cultivated longest is Vicia faba, the broad bean, which is thought to have originated in South West Asia. It is also known as the Windsor, or horse, bean and is extensively grown in Europe for human consumption and fodder. The pods grow up to 20 cm in length and the seeds are flat and broad. Several varieties are grown and may be obtained fresh, frozen, dried, canned or crushed (for stock feed). The genus Phaseolus is more widely grown throughout the world and includes kidney beans, string and lima beans, mung beans, teparies and runners.
Throughout the world, beans are among the most important food crops. They can be dried, ground into flour, canned, or frozen, and they can be stored for long periods without losing their flavor or nutritional value. Because of their high protein content, dried beans are very nutritious and make an excellent substitute for meat. They also contain carbohydrates, vitamin B15 calcium, and phosphorus. Both the pods and seeds of some beans, such as snap beans, are edible, but only the seeds of others, such as lima beans and red kidney beans, are used as food.
Beans are high in carbohydrates and a valuable source of protein, especially in poorer countries. They can be eaten in their immature form as greenbeans and pods or in their mature form as fully grown seeds. Some species are grown as green manure, whereas others are used as green feed for grazing stock. Seeds of some plants are commonly called beans even though they do not belong to the bean family; for example, the coffee bean, the castor bean and the Mexican jumping bean.
Bean plants vary in height from low bushy plants to large climbing plants, called pole beans, that twine their stems around poles, trellises, and other supports. In this respect beans differ from peas and some other legumes that cling to supports by threadlike tendrils. Most bean plants have leaflets, which grow in groups of three, and bear clusters of white, yellow, red, or purple flowers that resemble the sweet pea flower. Bean flowers ripen into straight or curved pods containing several seeds.
When both the seeds and pods are to be eaten, the beans are harvested while the pods are immature and the seeds are small. When only the seeds are to be eaten, the pods are harvested while the seeds are plump but still unripe. Navy beans, kidney beans, and other dried beans are picked when the seeds are ripe, but before they have become coarse and hard.
Beans are sown at the end of winter, when the danger of frost is over. They like an open, sunny position and plenty of moisture. For this reason they are usually planted after spring frosts. Some fast-growing beans may be ready for harvesting within 6 weeks. Others, including the lima bean, may need a growing season of 120 to 140 days. Sometimes several crops of the faster-growing kinds are raised in one season. Snap beans intended for human consumption are now being picked by machines, and mature beans are harvested by combines. Bean plants raised for livestock feed are harvested whole.
Beans are subject to attack by several insects, including the bean weevil and beetle, and fungus and virus diseases, such as anthracnose and rust. A certain degree of control is obtained by planting disease-free seeds or known resistant varieties, or by spraying or dusting with pesticides. Crop rotation is another method of controlling some infestations.
The most widely cultivated of all beans in the United States and Canada are the kidney beans. Some of the best-known varieties include the common red kidney bean, the speckled pinto bean, the white navy bean, the snap bean, and a yellow variety called the wax bean. Varieties whose dried, hard seeds are eaten are called dry beans.
In the United States the largest producers of red kidney beans are Michigan, New York, and California. Pinto beans are widely cultivated in Colorado and Idaho, and navy beans in Michigan and New York. Most snap beans and wax beans are raised in Florida, New York, Oregon, and Maryland.
The lima, or sugar, bean may be either a dwarf bush plant or a stout climbing plant that grows 10 feet tall and bears broad, flat green pods with pointed tips. The edible seeds are relatively large and flat, and are usually pale green. Several varieties, called potato lima beans, are cultivated for their small, unusually tender seeds. Most of the lima beans grown in the United States are raised in California.
The broad bean, which is also called the Windsor bean, horsebean, or English bean, is a hardy leafy plant that grows from 2 to 6 feet tall. Its large, thick pod is usually 2 to 4 inches long, but may be more than 12 inches long in some varieties. Its seeds may be brown, green, purple, or black, and they resemble lima beans in shape and taste. Canada and California are large producers of broad beans.
Although their pods are edible, several species of beans are raised chiefly as ornamental plants, particularly in warmer southern areas of the United States. The best known include the scarlet runner bean, a tall climbing plant with clusters of brilliant-red flowers, and the hyacinth bean, a twining plant that grows up to 20 feet high and bears white or purple flowers.