LEGUMES



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Legumes - seeds of members of the Fabaceae - p. 137-138

Introduction
Legumes are second only to the grasses in their importance to humans and our domestic animals. Every major civilization has been based on a cereal grain as well as a legume.
Legumes are by definition all members of the Fabaceae or Leguminosae. This is a large family with perhaps 16,000 species. Usually broken down into three subfamilies. Almost all important crop legumes in the Faboideae or Papilionoideae. The fruit is a legume. This is a single carpel that splits along two longitudinal margins at maturity to release its seeds. Commonly known as "pods".
Many important legumes in table on page 143. Diagram of legume flowers and fruits p. 137-138.
The roots of most legumes form associations with bacteria that are capable of fixing atmospheric nitrogen. These Rhizobiumspecies live in nodules on the roots. They provide free fertilizer. Flowering plants cannot use atmospheric nitrogen but must absorb nitrate or ammonium nitrogen through the roots. Nitrogen cycle on pg. 140.
Legumes also are rich in protein (which contains nitrogen). See table on pg. 142 for nutritional composition. Many are in the 20-30% range. They also contain some fats and usually less starches than cereal grains. Amino acid composition is different and these seeds contain more of some amino acids than cereal grains do.
The seeds of almost all legumes are toxic if eaten uncooked because of proteins or peptides that inhibit digestive enzymes.
World production... see page 144. Discuss what common beans are.
Important points: There are many ancient cultivars. Near East and Europe: peas, broad beans, lentils, and garbanzos. New World: common beans, lima beans, and peanuts South East Asia and China: soy beans, mung beans (Vigna aureus) and adjuki bean (Vigna mungo. Africa: black-eyed pea, pigeon pea.

Legumes in a market

Domestication of legumes
Lentils one of oldest. Wild small-seeded legumes used. By 6000 B.C. peas, vetch ( Viciasp.), bitter vetch (Vicia ervilia), and garbanzos were already cultivated. In Africa Vigna by 2000 B.C. In the Americas, Phaseolus coccineusin Tamps. by 5000 B.C. wild harvested. By 4000 B.C., P. vulgarisand P. lunatuswere cultivated in Peru. etc.
Many domesticated legumes have lost the ability to reseed themselves. Pods of cultivars are indehiscent.

Lentils
These legumes (Lens culinaris) are among the most ancient of cultivated crops. They go back 8000-9000 years in the Near East. They are found in archaeological sites before that, but as is the case for cereal grains, it is difficult to sort out what is cultivated and what is not. Esau sold his birthright to Jacob for a bowl of lentils. By 2200 B.C., they appear in Egyptian tombs. They are especially high in protein. Lentils are particularly important in India today. They have many different kinds of "dhal". They are drought resistant.
In the U.S. mostly in Washington and Idaho in the Palouse Prairies.


Lentils

Peas
Peas (Pisum sativum) are also an extremely old crop from the Near Eastern center. They go back at least 9000 years. They may have also come from Ethiopia and Central Asia. In the Middle Ages in Europe, dried peas made up a major part of the diet of peasants. Still very important there, especially in Eastern Europe. People didn't eat "green peas" until about the 1700's, however. Although mostly of a novelty for us, peas are the fourth most important legume crop world wide.


Peas

Broad beans
Broad beans ( Vicia faba) were also domesticated in the Near Eastern Center. The cultivation of these beans goes back to Egyptians, Romans, Greeks, etc. The only common bean in Europe before 1492. Production spread to Asia at some time in the past and today China is the world's largest producer of broad beans.
The Spanish brought them to the New World. They grow best in a cool climate. Canada produces more than the U.S. They cause "favism" in some people that eat them. A genetic disorder.

Broad beans

Garbanzos or chick peas
Another legume from the Near Eastern Center that was cultivated by 7400 years ago. This species may have arisen in Northeast Africa. By 2000 B.C. they were introduced into India. India now grows 79% of world's crop. Cultivation spread around the Mediterranean and they were brought to the New World by the Spanish and Portugese.

Soybeans
Soybeans (Glycine max) arose in China. They go back there at least 7000 years. In Chinese literature before 1000 B.C. About 38% protein and 18% fats and oils. The amino acid content is especially good. They also serve as a source of edible oils.
In the orient soybeans are eaten in many different ways. They are converted to miso, tofu, okara, soy milk, soy sauce, curd, cheeses, greens (sprouts), etc.
Although soybeans were introduced to Europe quite early, they never became popular. Pennsylvania by 1804. Until the 1940's they never really were grown much in the United States. Benjamin Franklin was sent a sample of seeds and both he and Thomas Jefferson grew them.
The coagulated protein is called tofu.
Most of the U.S. soybean crop is consumed indirectly. Over half of our production is exported. Much is used in this country as "texturized vegetable protein". About 15% of crop used for industrial purposes. Soy beans are the most important bean crop in the world.


Soybeans

Pigeon peas
Pigeon peas (Cajanus cajan) are commonly cultivated in the Caribbean area, although they are native to Africa and were introduced by black slaves. They go back perhaps 4000 years in Africa. This legume is also widely cultivated in India, which grows 95% of the world's crop. They do well on poor soils.


Black-eyed peas

In a similar manner, Vigna unguiculata, was domesticated in Africa and brought to the Americas by black slaves. Other species of the genus are also widely cultivated in Asia. These or related species were in India by "Sanskrit times". Romans and Greeks knew them.
They are mostly grown in Texas, Georgia, Oklahoma, and the Carolinas in the U.S.

Asian Vigna species.
Many species of this genus are cultivated in Asia. Among these are the black gram or urd bean (Vigna mungo), the mung bean (V. aureus), the adjuki bean (V. angularis) and others. These are usually included in "bean" statistics and make them difficult to interpret.

Mung beans
Lima beans
The lima bean, Phaseolus lunatus, may have been independently domesticated in Mexico and in northern South America. It appears to have spread southward into other parts of South America. The oldest cultivated materials are from Peru (7000-10000 years old).
Domestication may have arisen in several different areas. In 1492, they were cultivated from Canada to Argentina.
These are usually perennials in the tropics. Many lima beans are highly toxic unless prepared properly. This is not true in the United States and Europe, however.


Lima beans

Scarlet runner bean.
This bean (Phaseolus coccineus) is an ancient cultivar in Mexico. They are still commonly eaten there and this is a common bean in Europe.


Scarlet runner beans

Common beans
Kidney beans, pinto beans, navy beans, black beans, green beans, wax beans, snap beans, etc. are all Phaseolus vulgaris. They were domesticated in Mexico and South America and almost certainly were domesticated several times. Fossil cultivated beans go back 7000 years in Mexico and almost as far in Peru.
Beans were commonly cultivated in all parts of the Americas when Columbus came. This species is the second or third most important bean crop in the world.
The American Indians commonly cultivated these with squash and corn. This was partly to provide support for the beans which were viny.

Common Beans

Peanuts
The peanut or groundnut (Arachis hypogaea) is native to central South America and was probably domesticated by the Guaraní Indians. By 2000 B.C. cultivated in Peru. The Portugese took peanuts to several parts of the world in the early 1500's and it is now hard to tell that they are not native. They were widely cultivated in Africa and were brought back to the Americas by black slaves.
Peanuts are an important crop in the southeastern U.S. in sandy soils. They largely replaced cotton in the South after the boll weevil became a major pest about 1900. Peanuts are widely eaten in West Africa today.
This is the second most important legums, but are often not eaten directly.
This legume contains more oil than most. Peanut oil is widely used in West Africa and in France. Usually used to fondue because of its higher temperature properties.
The fruits are borne under the ground. Much U.S. production goes into peanut butter.
Aflatoxin is a major problem.

Peanuts

Tamarind and Carob
Tamarinds (Tamarindus indica) have been used in tropical Africa and Asia for thousands of years. The sticky pulp has a sour taste and is the part used. They are used in many types of sauces. See diagram pg. 152.
Carob (Ceratonia siliqua) has also been cultivated in the Near East for thousands of years. The fruits have long been used to feed livestock. Carob is currently used as a chocolate substitute and as a source of "locust gum".

Prosopisspecies.
Many of the pods eaten formerly in Argentina and Chile. Called "patay". Made from Prosopis nigraor albarobilla.



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Revised January 2005


© David S. Seigler, Integrative Biology 363, Plants and Their Uses, Department of Plant Biology, 265 Morrill Hall, 505 S. Goodwin Ave., University of Illinois, Urbana, Illinois 61801, USA. 217-333-7577. seigler@life.uiuc.edu.