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Legume

Legume

Overview
A legume (ˈlɛɡuːm) in botanical writing
Botany
Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...

 is a plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

 in the family Fabaceae
Fabaceae
The Fabaceae or Leguminosae, commonly known as the legume, pea, or bean family, is a large and economically important family of flowering plants. The group is the third largest land plant family, behind only the Orchidaceae and Asteraceae, with 730 genera and over 19,400 species...

 (or Leguminosae), or a fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

 of these specific plants. A
legume fruit is a simple dry fruit that develops from a simple carpel and usually dehisces
Dehiscence (botany)
Dehiscence is the opening, at maturity, in a pre-defined way, of a plant structure, such as a fruit, anther, or sporangium, to release its contents. Sometimes this involves the complete detachment of a part. Structures that open in this way are said to be dehiscent...

 (opens along a seam) on two sides. A common name for this type of fruit is a pod, although the term "pod" is also applied to a few other fruit types, such as vanilla
Vanilla
Vanilla is a flavoring derived from orchids of the genus Vanilla, primarily from the Mexican species, Flat-leaved Vanilla . The word vanilla derives from the Spanish word "", little pod...

 and radish
Radish
The radish is an edible root vegetable of the Brassicaceae family that was domesticated in Europe, in pre-Roman times. They are grown and consumed throughout the world. Radishes have numerous varieties, varying in size, color and duration of required cultivation time...

.
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Encyclopedia
A legume (ˈlɛɡuːm) in botanical writing
Botany
Botany, plant science, or plant biology is a branch of biology that involves the scientific study of plant life. Traditionally, botany also included the study of fungi, algae and viruses...

 is a plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

 in the family Fabaceae
Fabaceae
The Fabaceae or Leguminosae, commonly known as the legume, pea, or bean family, is a large and economically important family of flowering plants. The group is the third largest land plant family, behind only the Orchidaceae and Asteraceae, with 730 genera and over 19,400 species...

 (or Leguminosae), or a fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...

 of these specific plants. A
legume fruit is a simple dry fruit that develops from a simple carpel and usually dehisces
Dehiscence (botany)
Dehiscence is the opening, at maturity, in a pre-defined way, of a plant structure, such as a fruit, anther, or sporangium, to release its contents. Sometimes this involves the complete detachment of a part. Structures that open in this way are said to be dehiscent...

 (opens along a seam) on two sides. A common name for this type of fruit is a pod, although the term "pod" is also applied to a few other fruit types, such as vanilla
Vanilla
Vanilla is a flavoring derived from orchids of the genus Vanilla, primarily from the Mexican species, Flat-leaved Vanilla . The word vanilla derives from the Spanish word "", little pod...

 and radish
Radish
The radish is an edible root vegetable of the Brassicaceae family that was domesticated in Europe, in pre-Roman times. They are grown and consumed throughout the world. Radishes have numerous varieties, varying in size, color and duration of required cultivation time...

. Well-known legumes include alfalfa
Alfalfa
Alfalfa is a flowering plant in the pea family Fabaceae cultivated as an important forage crop in the US, Canada, Argentina, France, Australia, the Middle East, South Africa, and many other countries. It is known as lucerne in the UK, France, Australia, South Africa and New Zealand, and known as...

, clover
Clover
Clover , or trefoil, is a genus of about 300 species of plants in the leguminous pea family Fabaceae. The genus has a cosmopolitan distribution; the highest diversity is found in the temperate Northern Hemisphere, but many species also occur in South America and Africa, including at high altitudes...

, pea
Pea
A pea is most commonly the small spherical seed or the seed-pod of the pod fruit Pisum sativum. Each pod contains several peas. Peapods are botanically a fruit, since they contain seeds developed from the ovary of a flower. However, peas are considered to be a vegetable in cooking...

s, bean
Bean
Bean is a common name for large plant seeds of several genera of the family Fabaceae used for human food or animal feed....

s, lentil
Lentil
The lentil is an edible pulse. It is a bushy annual plant of the legume family, grown for its lens-shaped seeds...

s, lupin
Lupin
Lupinus, commonly known as Lupins or lupines , is a genus in the legume family . The genus comprises about 280 species , with major centers of diversity in South and western North America , and the Andes and secondary centers in the Mediterranean region and Africa Lupinus, commonly known as Lupins...

s, mesquite
Mesquite
Mesquite is a leguminous plant of the Prosopis genus found in northern Mexico through the Sonoran Desert and Chihuahuan Deserts, and up into the Southwestern United States as far north as southern Kansas, west to the Colorado Desert in California,and east to the eastern fifth of Texas, where...

, carob, soy, and peanut
Peanut
The peanut, or groundnut , is a species in the legume or "bean" family , so it is not a nut. The peanut was probably first cultivated in the valleys of Peru. It is an annual herbaceous plant growing tall...

s. Locust trees (Gleditsia
Gleditsia
Gleditsia is a genus of locust trees in the family Fabaceae, subfamily Caesalpinioideae, native to North America and Asia. The Latin name commemorates Johann Gottlieb Gleditsch, director of the Berlin Botanical Gardens, who died in 1786....

or Robinia
Robinia
Robinia is a genus of flowering plants in the family Fabaceae, subfamily Faboideae, native to North America and northern Mexico. Commonly known as "locusts", they are deciduous trees and shrubs growing 4-25 m tall. The leaves are pinnate with 7-21 oval leaflets. The flowers are white or pink, in...

), wisteria
Wisteria
Wisteria is a genus of flowering plants in the pea family, Fabaceae, that includes ten species of woody climbing vines native to the eastern United States and to China, Korea, and Japan. Aquarists refer to the species Hygrophila difformis, in the family Acanthaceae, as Water Wisteria...

, and the Kentucky coffeetree
Kentucky coffeetree
The Kentucky Coffeetree, Gymnocladus dioicus, is a tree in the subfamily Caesalpinioideae of the pea family Fabaceae, native to the midwest of North America.-Introduction:...

 (Gymnocladus dioicus) are also legumes.

History




The term legume is derived from the Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

 word legumen (with the same meaning as the English term), which is in turn believed to come from the verb legere which means "to gather." English borrowed the term from the French
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...

 "légume," which, however, has a wider meaning in the modern language and refers to any kind of vegetable
Vegetable
The noun vegetable usually means an edible plant or part of a plant other than a sweet fruit or seed. This typically means the leaf, stem, or root of a plant....

; the English word legume being translated in French by the word légumineuse.

The history of legumes is tied in closely with that of human civilization
Civilization
Civilization is a sometimes controversial term that has been used in several related ways. Primarily, the term has been used to refer to the material and instrumental side of human cultures that are complex in terms of technology, science, and division of labor. Such civilizations are generally...

, appearing early in Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...

, the Americas
Americas
The Americas, or America , are lands in the Western hemisphere, also known as the New World. In English, the plural form the Americas is often used to refer to the landmasses of North America and South America with their associated islands and regions, while the singular form America is primarily...

 (the common Phaseolus bean
Common bean
Phaseolus vulgaris, the common bean, is an herbaceous annual plant domesticated independently in ancient Mesoamerica and the Andes, and now grown worldwide for its edible bean, popular both dry and as a green bean. The leaf is occasionally used as a leaf vegetable, and the straw is used for fodder...

 in several varieties), and Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

 (broad beans), where they became a staple, essential for supplementing protein where there was not enough meat.

Fixation of nitrogen in the soil



Legume plants are notable for their ability to fix atmospheric nitrogen
Nitrogen fixation
Nitrogen fixation is the natural process, either biological or abiotic, by which nitrogen in the atmosphere is converted into ammonia . This process is essential for life because fixed nitrogen is required to biosynthesize the basic building blocks of life, e.g., nucleotides for DNA and RNA and...

, thanks to a mutualistic symbiotic
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

 relationship with bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...

 (rhizobia
Rhizobia
Rhizobia are soil bacteria that fix nitrogen after becoming established inside root nodules of legumes . Rhizobia require a plant host; they cannot independently fix nitrogen...

) found in root nodules of these plants. The ability to form this mutualism reduces fertilizer
Fertilizer
Fertilizer is any organic or inorganic material of natural or synthetic origin that is added to a soil to supply one or more plant nutrients essential to the growth of plants. A recent assessment found that about 40 to 60% of crop yields are attributable to commercial fertilizer use...

 costs for farmers and gardeners who grow legumes, and allows legumes to be used in a crop rotation
Crop rotation
Crop rotation is the practice of growing a series of dissimilar types of crops in the same area in sequential seasons.Crop rotation confers various benefits to the soil. A traditional element of crop rotation is the replenishment of nitrogen through the use of green manure in sequence with cereals...

 to replenish soil that has been depleted of nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...

. The nitrogen fixation
Nitrogen fixation
Nitrogen fixation is the natural process, either biological or abiotic, by which nitrogen in the atmosphere is converted into ammonia . This process is essential for life because fixed nitrogen is required to biosynthesize the basic building blocks of life, e.g., nucleotides for DNA and RNA and...

 ability of legumes is enhanced by the availability of calcium in the soil and reduced by the presence of ample nitrogen.

Legume seed and foliage have a comparatively higher protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 content than non-legume material, probably due to the additional nitrogen that legumes receive through nitrogen-fixation symbiosis
Symbiosis
Symbiosis is close and often long-term interaction between different biological species. In 1877 Bennett used the word symbiosis to describe the mutualistic relationship in lichens...

. The high protein content makes them desirable crops in agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...

.

Uses by humans



Farmed legumes can belong to many agricultural classes, including forage
Forage
Forage is plant material eaten by grazing livestock.Historically the term forage has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used more loosely to include similar plants cut for fodder and carried to the animals, especially...

, grain
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...

, blooms, pharmaceutical/industrial, fallow/green manure, and timber species. Most commercially farmed species fill two or more roles simultaneously, depending upon their degree of maturity when harvested.

Forage legumes are of two broad types. Some, like alfalfa
Alfalfa
Alfalfa is a flowering plant in the pea family Fabaceae cultivated as an important forage crop in the US, Canada, Argentina, France, Australia, the Middle East, South Africa, and many other countries. It is known as lucerne in the UK, France, Australia, South Africa and New Zealand, and known as...

, clover
Clover
Clover , or trefoil, is a genus of about 300 species of plants in the leguminous pea family Fabaceae. The genus has a cosmopolitan distribution; the highest diversity is found in the temperate Northern Hemisphere, but many species also occur in South America and Africa, including at high altitudes...

, vetch (Vicia
Vicia
Vicia is a genus of about 140 species of flowering plants commonly known as vetches. It is in the legume family . Member species are native to Europe, North America, South America, Asia and Africa. Some other genera of their subfamily Faboideae also have names containing "vetch", for example the...

), stylo (Stylosanthes), or Arachis
Arachis
Arachis is a genus of about 70 species of annual and perennial flowering plants in the pea family , native to South America. At least one species, the peanut , is a major food crop species of global importance; some of the other species are cultivated for food to a small extent in South America....

, are sown in pasture
Pasture
Pasture is land used for grazing. Pasture lands in the narrow sense are enclosed tracts of farmland, grazed by domesticated livestock, such as horses, cattle, sheep or swine. The vegetation of tended pasture, forage, consists mainly of grasses, with an interspersion of legumes and other forbs...

 and grazed by livestock. Other forage legumes such as Leucaena
Leucaena
Leucaena is a genus of flowering plants in the subfamily Mimosoideae of the legume family Fabaceae. It contains about 24 species of trees and shrubs, which are commonly known as Leadtrees. They are native to the Americas, ranging from Texas in the United States south to Peru...

or Albizia
Albizia
Albizia is a genus of about 150 species of mostly fast-growing subtropical and tropical trees and shrubs in the subfamily Mimosoideae of the legume family, Fabaceae. The genus is pantropical, occurring in Asia, Africa, Madagascar, Central, South, and southern North America and Australia, but mostly...

are woody shrub or tree species that are either broken down by livestock or regularly cut by humans to provide livestock feed.

Grain legumes are cultivated for their seed
Seed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...

s, and are also called pulses
Pulse (legume)
A pulse is an annual leguminous crop yielding from one to twelve seeds of variable size, shape, and color within a pod. Pulses are used for food and animal feed. The term "pulse", as used by the Food and Agricultural Organization , is reserved for crops harvested solely for the dry seed...

. The seeds are used for human and animal consumption or for the production of oils for industrial uses. Grain legumes include bean
Bean
Bean is a common name for large plant seeds of several genera of the family Fabaceae used for human food or animal feed....

s, lentil
Lentil
The lentil is an edible pulse. It is a bushy annual plant of the legume family, grown for its lens-shaped seeds...

s, lupin
Lupin
Lupinus, commonly known as Lupins or lupines , is a genus in the legume family . The genus comprises about 280 species , with major centers of diversity in South and western North America , and the Andes and secondary centers in the Mediterranean region and Africa Lupinus, commonly known as Lupins...

s, pea
Pea
A pea is most commonly the small spherical seed or the seed-pod of the pod fruit Pisum sativum. Each pod contains several peas. Peapods are botanically a fruit, since they contain seeds developed from the ovary of a flower. However, peas are considered to be a vegetable in cooking...

s, and peanut
Peanut
The peanut, or groundnut , is a species in the legume or "bean" family , so it is not a nut. The peanut was probably first cultivated in the valleys of Peru. It is an annual herbaceous plant growing tall...

s.

Legume species grown for their flowers include lupins, which are farmed commercially for their blooms as well as being popular in gardens worldwide. Industrially farmed legumes include Indigofera
Indigofera
Indigofera is a large genus of about 700 species of flowering plants belonging to the family Fabaceae.The species are mostly shrubs, though some are herbaceous, and a few can become small trees up to tall. Most are dry-season or winter deciduous. The leaves are pinnate with 5–31 leaflets and the...

and Acacia
Acacia
Acacia is a genus of shrubs and trees belonging to the subfamily Mimosoideae of the family Fabaceae, first described in Africa by the Swedish botanist Carl Linnaeus in 1773. Many non-Australian species tend to be thorny, whereas the majority of Australian acacias are not...

species, which are cultivated for dye
Dye
A dye is a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and requires a mordant to improve the fastness of the dye on the fiber....

 and natural gum
Natural gum
Natural gums are polysaccharides of natural origin, capable of causing a large viscosity increase in solution, even at small concentrations. In the food industry they are used as thickening agents, gelling agents, emulsifying agents, and stabilizers...

 production, respectively. Fallow/green manure
Green manure
In agriculture, a green manure is a type of cover crop grown primarily to add nutrients and organic matter to the soil. Typically, a green manure crop is grown for a specific period of time , and then plowed under and incorporated into the soil while green or shortly after flowering...

 legume species are cultivated to be tilled back into the soil in order to exploit the high levels of captured atmospheric nitrogen found in the roots of most legumes. Numerous legumes farmed for this purpose include Leucaena, Cyamopsis
Cyamopsis
Cyamopsis is a genus of the family Fabaceae. Its species are distributed across Africa, Asia and the Pacific....

, and Sesbania
Sesbania
Sesbania is a genus of flowering plants in the pea family, Fabaceae and the only genus found in Tribe Sesbanieae. Notable species include the Rattlebox , Spiny Sesbania , and Sesbania sesban, which is used in cooking...

species. Various legume species are farmed for timber production worldwide, including numerous Acacia species and Castanospermum australe.

Nutritional facts


Legumes contain relatively low quantities of the essential amino acid
Essential amino acid
An essential amino acid or indispensable amino acid is an amino acid that cannot be synthesized de novo by the organism , and therefore must be supplied in the diet.-Essentiality vs. conditional essentiality in humans:...

 methionine
Methionine
Methionine is an α-amino acid with the chemical formula HO2CCHCH2CH2SCH3. This essential amino acid is classified as nonpolar. This amino-acid is coded by the codon AUG, also known as the initiation codon, since it indicates mRNA's coding region where translation into protein...

. To compensate, some vegetarian cultures serve legumes along with grain
Cereal
Cereals are grasses cultivated for the edible components of their grain , composed of the endosperm, germ, and bran...

s, which are low in the essential amino acid lysine
Lysine
Lysine is an α-amino acid with the chemical formula HO2CCH4NH2. It is an essential amino acid, which means that the human body cannot synthesize it. Its codons are AAA and AAG....

, which legumes contain. Thus a combination of legumes with grains can provide all necessary amino acids for vegetarians. Common examples of such combinations are dal
Dal
Dal is a preparation of pulses which have been stripped of their outer hulls and split. It also refers to the thick stew prepared from these, an important part of Indian, Nepali, Pakistani, Sri Lankan, and Bangladeshi cuisine...

 with rice
Rice
Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...

 by Indians, and beans with corn tortillas, tofu
Tofu
is a food made by coagulating soy milk and then pressing the resulting curds into soft white blocks. It is part of East Asian and Southeast Asian cuisine such as Chinese, Japanese, Korean, Indonesian, Vietnamese, and others. There are many different varieties of tofu, including fresh tofu and tofu...

 with rice, and peanut butter
Peanut butter
Peanut butter is a food paste made primarily from ground dry roasted peanuts, popular in North America, Netherlands, United Kingdom, and parts of Asia, particularly the Philippines and Indonesia. It is mainly used as a sandwich spread, sometimes in combination as in the peanut butter and jelly...

with wheat bread.

External links


  • AEP - European association for grain legume research
  • Lupins - Geography, classification, genetic resources and breeding
  • ILDIS - International Legume Database & Information Service
  • Bioversity International The significance of Vavilov’s scientific expeditions and ideas for development and use of legume genetic resources
  • Legume Futures A major research initiative to develop novel uses for legumes in environmentally and economically sustainable cropping.