Bean - biology.

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Bean - biology.
Bean, common name widely applied to many plants of the legume family. The seeds and pods of these plants are used for food and forage. The seeds themselves are
also called beans and are valuable as food because of their high protein content. The term bean is also applied to plants of other families, such as the Indian bean,
which is a North American species, and the sacred bean, or Indian lotus. The seeds or fruits of certain other plants, such as the coffee tree and the castor-oil plant (see
Castor Bean), are also called beans.
The broad bean, also called horsebean or Windsor bean, has been cultivated since prehistoric times and is still the most common bean in many parts of Europe. Various
species are cultivated in the United States under the name of vetch. Most of the beans of the United States and the frijoles of Mexico belong to the same genus. The
cowpea, asparagus bean, and hyacinth bean are also cultivated, particularly for forage. The soybean is a common bean in Asian countries and has been more widely
cultivated in the United States in recent years than have native varieties of bean. Most soybeans are grown today for their oil, which is used in industrial manufacturing
and as fodder for livestock. Another popular bean in Asia is the mung bean. Mung bean sprouts are frequently used as a vegetable accompaniment in Chinese cooking,
and mung bean starch is used to make noodles.
The wild bean of the United States is rarely cultivated. Hundreds of varieties of the common garden bean of the United States are cultivated. The young pods are called
string, or snap, beans if green; they are called wax, or butter, beans if yellowish. The seeds of the older pods are known as shell beans. The small variety is often called
navy bean and the large purplish variety, kidney bean.
The next most important species in the United States is the lima, or sugar, bean, regarded by some botanists as a variety of the civet bean. Because it is drought
resistant, the tepary is cultivated in Mexico and in the southwestern United States. The scarlet runner is often cultivated in Europe, as much for its attractive red flowers
as for its edible beans.
For cultivating, beans are divided into two groups: pole beans, or vines requiring a pole for support; and bush beans, erect shrubs of low, spreading growth. Many of
the species, notably the common garden bean of the United States, have varieties in both groups, and the groups overlap one another. Although some of the bean
plants are perennials, most of the important cultivated species are annuals and are sown in rich, loose, warm soil after all danger of frost is past.
The principal disease affecting beans is a form of anthracnose caused by a fungus that attacks the stems, leaves, and pods of the bean. It is most visible on pods, in
which it causes deep, dark pits. To prevent the disease, seeds are carefully selected, and care is taken not to spread the fungus from one plant to another during wet
weather. A rust may defoliate bean plants. It first appears as small brown dots containing a brown powder, the spores of the fungus. Later the spots become larger and
the spores black.
Scientific classification: Most beans belong to the subfamily Papilionoideae of the family Fabaceae (formerly Leguminosae). The Indian bean is classified in the genus
Catalpa. The broad bean is classified as Vicia faba. Vetch is classified in the genus Vicia. Most beans of the United States and the frijoles of Mexico are classified in the
genus Phaseolus. Cowpeas and asparagus beans are classified in the genus Vigna. The hyacinth bean is classified as Lablab purpureus, the soybean as Glycine max, the
wild bean of the United States as Phaseolus polystachios, and the common garden bean of the United States as Phaseolus vulgaris. The lima, or sugar, bean is
generally classified as Phaseolus limensis, although it is regarded by some as a variety of the civet bean, classified as Phaseolus lunatus. The tepary is classified as
Phaseolus acutifolius variety latifolius and the scarlet runner as Phaseolus coccineus.

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