legume

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The term "legume" refers both to the plants whose fruit is enclosed in a pod and to the family these plants belong to (Leguminosae). The legumes represent a vast family of plants including more than 600 genera and more than 13,000 species. 



Tips for preparing legumes

Most dried legumes must be soaked before cooking. Soaking rehydrates dried legumes (called "pulses"), reduces their cooking time and preserves their vitamins and minerals. It also reduces gas-related problems. Some legumes do not need soaking. Legumes are generally soaked for 6-8 hr, but this soaking time can be shortened or omitted if using a pressure cooker. Dried legumes can be soaked in large quantities and a portion of them frozen.

Long soaking 

Discard damaged beans and any foreign matter. Wash dried legumes several times in cold water and leave to soak. Discard any impurities or beans that float to the surface. Place the dried legumes in a large bowl, cover with three parts water to one part legumes and let soak overnight in a cool place or in the fridge.

Quick soaking

Place in 3-4 cups (750-1,000 ml) water for 1 cup (250 ml) of dried legumes (about 6.5 oz/185 g), then bring gently to a boil. Let simmer for 2 min, cover and remove from heat. Let rest for 1-2 hr, until the beans have swollen in size. Drain and cook according to the recipe. If using a microwave oven, place dried legumes in a dish large enough to contain them when they swell; cover with cold water and cook on the highest setting for 8-10 min or until they boil. Continue to boil for 2 min, then let rest for 1 hr.
There are some precautions that can be taken to reduce gas problems provoked by legumes: 

      • Remove the outer skin of dried legumes before eating.

      • Do not use the soaking water for cooking; the soaking water can also be changed a few times, or cook the legumes for 30 min, then change the cooking water and cook until very tender. Changing the cooking or soaking water does, however, lead to a loss of nutrients; this can be reduced by adding a little food yeast at time of serving.

      • Cook slowly and thoroughly.

      • Chew well and avoid finishing the meal with a sweet dessert, or adding sweet ingredients during the cooking of the legumes.


Tips for cooking legumes

After soaking, legumes can be cooked on the stovetop, in the oven or in a pressure cooker.

Cooking on the stovetop and in the oven

This slow-cooking method is best if the legumes are cooked with other ingredients, as they will then absorb all of the flavors. Cover dried legumes with cold water, bring to a boil, reduce heat and let simmer until the legumes are tender (usually about 2 hr).

Cooking in a pressure cooker

This method of cooking is quicker, but is best when there are not many cooking ingredients and seasonings added at the beginning of cooking. Pressure-cooking involves certain risks, especially for dried legumes that produce higher amounts of scum, such as soybeans, lima beans and the various peas. It is not recommended for lentils and split peas. For good results:

      • Add a little oil to the cooking liquid to prevent scum from forming (the valve and pressure regulator could become blocked). Beans cooked in the pressure cooker should be brought to a boil uncovered, then remove any scum that forms. Lower the heat, let simmer and cover with the lid to pressure-cook; time cooking carefully once the desired pressure is reached.

      • Do not cook too large a quantity of dried legumes (do not fill the pressure cooker more than one-third of its volume), as most double or triple their size during cooking. 

      • Do not cook over a high heat. Run the pot under cold water as soon as the cooking time is over. Always clean the valve and pressure regulator well after use to prevent them from becoming blocked (if they become blocked, put the pressure cooker under cold water immediately and clean them).
To reduce cooking time and make legumes tender, some baking soda can be added to the cooking or soaking liquid. However, this destroys part of the legumes' thiamine content, reduces the absorbability of their amino acids and often alters their flavor. Adding a little seaweed slightly reduces the cooking time, tenderizes dried legumes and adds to their nutritional value.

Salt and acid ingredients (tomato, vinegar, lemon juice) are added at the end of cooking time, as they harden dried legumes and extend cooking time. If more water needs to be added during cooking, use boiling water. 

Do not cook two varieties of legume at the same time, even if in principle they require the same cooking time; they will rarely cook evenly. Cook separately. Most legumes contain substances that diminish their nutritional value, but cooking the legumes well eliminates these substances.

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For more information on legume, visit Britannica.com.

A member of the plant family Leguminosae, and the name for the fruit produced by members of that family, as idealized in a bean or pea pod. The legume and grass families are by far the world's most important sources of food. Legumes, which include beans, soybeans, peas, and alfalfa, supply protein and fats. Through their root nodules, which are inhabited by Rhizobium bacteria, the legumes also preserve the nitrogen balance in the soil. Legumes comprise one of the largest plant families in the world, with perhaps 18,000 species. Most speciesare tropical and include trees, woody vines, and herbaceous plants. All legume plants bear the same type of fruit, the pod or legume, which is diversely modified within the family. Most have compound leaves, and many, particularly tropical legumes, have spectacular flowers, some of which are grown as ornamentals. See also Fabales; Grass crops; Nitrogen fixation.

The three major groups of Leguminosae differ in the appearance of their flowers, and some botanists consider them to be three separate families. Others, as here, regard them as a single diverse family because all have the same kind of fruit and because the groups intergrade. The first group is the Mimosoids, in which the flowers have reduced petals and usually have conspicuous, long stamens that give color to the flower clusters. The Mimosoid group, which is almost entirely tropical, includes the so-called sensitive plant and the silk tree, or mimosa, a widely planted ornamental in the southern United States. The second group, the Caesalpinioids, is characterized by well-developed petals and includes ornamentals such as the redbud and honey locust in temperate regions and the orchid trees of the tropics. The third and largest group is the Papilionoids, whose members bear a flower that resembles the sweet pea, with a big petal at the top, a wing on either side, and a “keel” of two fused petals that enclose the stamens at the bottom. Many important agricultural plants are members of the Papilionoid group, including peanuts, garden beans, soybeans, garden peas, lentils, chickpeas, cowpeas, clovers, and alfalfa. See also Alfalfa; Bean; Clover; Cowpea; Lentil; Pea; Peanut; Soybean.

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Members of the family Leguminosae consumed as dry mature seeds (grain legumes or pulses) or as immature green seeds in the pod. On boiling, the dried seeds double in weight, so a 100-g cooked portion is approximately 50 g as a dried product.

Legumes include the groundnut, Arachis hypogaea, and soya bean, Glycine max, grown for their oil and protein, the yam bean Pachyrrhizus erosus, and African yam bean Sphenostylis stenocarpa, grown for their edible tubers as well as seeds. See also beans.

[lehg-YOOM] Any of thousands of plant species that have seed pods that split along both sides when ripe. Some of the more common legumes used for human consumption are beans, lentils, peanuts, peas and soybeans. Others, such as clover and alfalfa, are used as animal fodder. When the seeds of a legume are dried, they're referred to as pulses. The high-protein legumes are a staple throughout the world. They contain some vitamin B, carbohydrates, fats and minerals. See also black-eyed pea; chickpea; english pea; field pea; winged bean; yard-long bean.

Legumes are the edible seeds of plants. They provide a good source of protein, thiamine, folic acid, vitamin E, and fiber. The insoluble fiber in legumes helps to lower blood cholesterol. Examples of legumes are: dried beans, peas, and seeds (including navy, broad, butter, northern, pinto, red, and black beans, as well as chick peas, soybeans, and peanuts).

Legumes are an important source of protein for vegetarians, especially vegans. The protein in legumes is considered incomplete, however, and needs to be eaten in combination with whole grains to make a complete (high-quality) protein (e.g., green beans, lentils, and rice; navy beans and barley; soybeans and sesame seeds; red beans and rice). Such combinations have been used for centuries in the diets of people practicing vegetarianism.

See also Plant-based diets; Soy; Vegetarianism.

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Legumes are members of a family of flowering plants known as Leguminosae. It is one of the three largest families of flowering plants, with approximately 690 genera and about 18,000 species. Legumes are a significant component of nearly all terrestrial biomes on all continents except Antarctica. Some are fresh water aquatics, but no truly marine species exist. The species within the family range from dwarf herbs among arctic and alpine vegetation to massive trees in tropical forests.

The leaves usually occur alternately on the stem and are compound, meaning each leaf is divided into separate leaflets. Both pinnate and trifoliate leaves exist. Legumes are easily recognized by the structure of the flower. The flowers are hermaphroditic with male (stamens) and female (pistils) parts in the same flower and usually with five sepals and five petals. The ovary has a single carpel, cavity, and style. The principal unifying feature of the family is the fruit, a pod technically known as a legume. The legume pod is modified in many ways, including flat, winged, thick, thin, straight, coiled, short, long, woody, fleshy, splitting open, or indehiscent to facilitate dispersal by animals, wind, and water.

The family is divided into three subfamilies: Papilionoideae, Caesalpinioideae, and Mimosoideae, identified by their flowers. The Papilionoideae is the largest of the three subfamilies and the most widespread, extending farther into temperate regions. This subfamily can be easily recognized by its butterfly-like flowers. Most of the important legume crop species consumed by humans, including soybean, field pea, chickpea, field bean, and peanut, are in this group.

The subfamily Caesalpinioideae is comprised of tropical or subtropical trees and shrubs. The useful products derived from this subfamily include edible fruits (Tamarindus indica), senna medicine (Senna spp.), hematoxylon red dye from the logwood tree (Haematoxylon campechianum), and resins used in paints, varnishes, inks, plastics, adhesives, and fireworks derived from the copal (Copaifera spp.) tree.

The subfamily Mimosoideae includes species of industrial, forage, browsing, and fodder importance, such as Acacia spp. (Bisby et al., 2000). The Australian black-wood (Acacia melanoxylon) tree provides useful timber, and gum arabic from the tree of that name (Acacia senegal) is used in an array of industrial processes.

Nitrogen Fixation

Most legumes convert atmospheric nitrogen into nitrogenous compounds useful to plants. Root nodules containing Rhizobium bacteria fix free nitrogen for the plants. In return, legumes supply the bacteria with carbon produced by photosynthesis. This symbiosis provides the nitrogen needed by the plants for survival. Root nodules form in all subfamilies except in rare cases among the Caesalpinioideae.

The basic process of nitrogen fixation involves penetration by the Rhizobium through the root hairs into the cortex, where cell division occurs. These tetraploid cells produce the nodules that appear on the root surface. The nodule growth and efficiency are influenced by the carbon-nitrogen ratio of the plant and by the presence in the soil of phosphate, calcium, magnesium, molybdenum, and boron. If the nodules are ineffective, the bacteria may be parasitic on the host plant. Effective nodules contain red leghemoglobin, which can be seen when the nodules are cut. Ineffective nodules are usually small, hard, spherical, and a greenish color inside. Legumes produce more nodules in the tropics in acid soils and soils deficient in phosphorus, calcium, and other nutrients than in temperate areas. Many strains of Rhizobium occur in nature with multiple hosts, and several Rhizobium species occur with one host (Purseglove, 1981). Many scientists suggest inoculating legume seeds with the appropriate strain of Rhizobium for best agricultural results. This inoculation technique is accomplished by mixing the Rhizobium in water to form a slurry and then adding it to the seed.

Origin

The primary temperate legumes used for human food include garden pea (Pisum sativum), field pea (Pisum arvense), winged pea (Tetragonolobus purpureus), green bean (Phaseolus vulgaris), runner bean (Phaseolus coccineus), butter bean (Phaseolus lunatus), lima bean (Phaseolus limensis), soybean (Glycine max), lentil (Lens culinaris), and broad bean (Vicia faba). These legumes originated in humid, subhumid, cool season, subtropical, semiarid, and temperate areas in diverse regions ranging from Southwest Asia and East Asia to the Mediterranean, Peru, Mexico, and Guatemala (Muehlbauer, 1993).

Common tropical legumes consumed by humans include winged bean (Psophocarpus tetragonolobus), jicama (Pachyrhizus erosus and Pachyrhizus tuberosus), chickpea (Cicer arietinum), black-eyed pea (Vigna unguiculata unguiculata), and peanut (Arachis hypogaea). These tropical legumes originated in areas characterized by humid, semiarid, cool season, subtropical, and tropical climates, primarily including South America, Southwest Asia, Ethiopia, India, Japan, China, and West Africa (Hymowitz, 1990).

History. Soybean, one of the most popular legumes, is one of the oldest cultivated crops. Cultivated soybeans probably arose from a wild type in Asia and moved to Europe and North America in the eighteenth century. Soybean soon became the third most important agronomic crop in the United States. Cowpeas were introduced to the West Indies and ultimately spread throughout the southern United States after the seventeenth century. Field beans (Phaseolus spp.) were cultivated by American Indians at the time of the European discovery of North America and soon were introduced to Europe. The popular peanut, introduced into the United States from Brazil when the colonies were established, was commercially developed in the mid-eighteenth century.

Peas, including garden peas, field peas, broad beans, lentils, and chickpeas, were introduced into the Americas from Europe and the Near East. Jicama is grown in Southeast Asia, Mexico, and Central America. Winged beans were introduced into more than sixty countries, primarily subtropical and tropical, after the mid-1970s.

Primary Food Legumes

Soybean (Glycine max). Soybean is the most important legume produced in the agricultural industry worldwide. It is an annual crop, is easy to grow, and is adapted to a temperate climate. A hot weather crop, soybean requires a minimum of 59°F (15°C) for seed germination and mean temperatures of 68–77°F (20°–25°C) for crop growth. Only moderate soil moisture is needed for germination and seedling establishment, but dry weather is essential for dry seed production. Soybeans suffer when the soil is waterlogged, and established plants tolerate drought.

Soybeans should be fertilized with phosphorous, potassium, and micronutrients, and they require typical agricultural field preparation. The important differences among soybean cultivars are day-length response, pest resistance, and production. These varieties are subdivided into groups according to tropical, subtropical, or temperate climate adaptation (Martin, 1988).

Several major obstacles obstruct optimum soybean production. Diseases cause one-eighth of all soybean losses. Noteworthy diseases and their causal agents include bacterial blight (Pseudomonas glycinea), bacterial pustule (Xanthomonas phaseoli var. sojense), and wildfire (Pseudomonas tabaci). However, the most devastating diseases are caused by fungi, including brown stem rot (Cephalosporium gregatum), stem canker (Diaporthe phaseolorum var. batatatis), pod and stem blight (Diaporthe phaseolorum var. sojae), brown spot (Septoria glycines), and sclerotial blight (Sclerotium rolfsii). Mosaic virus disease, root knot nematode (Meloidogyne spp.), and cyst nematode (Heterodera glycines) also cause significant soybean losses.

The chemical composition of mature soybeans varies with the cultivar plus the soil and climate conditions. Generally, the black-seeded cultivars are protein rich with low oil content, and the yellow-seeded types are oil rich with low protein. The nutritional components of dried seeds are 5.0 percent to 9.4 percent water, 29.6 percent to 50.3 percent protein, 13.5 percent to 24.2 percent fat, 14.0 percent to 23.9 percent carbohydrate, 2.8 percent to 6.3 percent fiber, and a large amount of vitamin B. Soybean seeds contain a higher amount of protein than any other pulse and most other foodstuffs.

Soybean oil is about 51 percent linoleic acid, 30 percent oleic acid, and 6.5 percent linolenic acid and is used as a cooking oil, salad oil, shortening, and margarine. Soybean flour is mixed with wheat flour in baked products, such as bread, cakes, cookies, and crackers, and it is also used in ice cream, candy, and pudding. In Asia soybeans are consumed as soybean milk, soy sauce, soups, drinks, breakfast foods, and vegetables. People in eastern Asia eat unripe seeds and dried seeds, and elsewhere these large seeds are consumed as shelled green beans or as dry beans. Both the Bansei and the Green Giant cultivars are among the more popular soybeans. In the West soybeans are a primary ingredient of Worcestershire sauce, made by mixing boiled beans with wheat flour and salt, then fermenting the mixture with the fungus Aspergillus oryzae for up to one week. The fermented beans are submerged in brine and exposed to the sun for several months to extract the flavor. In Indonesia boiled beans are fermented with Aspergillus and formed into cakes.

Soybeans are used industrially in paints, linoleum, inks, soaps, insecticides, and disinfectants. Soy meal, the residue of oil extraction, is a healthy livestock feed (Purseglove, 1981). Soybeans are also used in the pharmaceutical and nutraceutical industries. For example, Ensure glucerna, a dietary aid for diabetics, includes soybeans, and Estroven, marketed as a dietary supplement with natural phytoestrogens, contains isoflavones, a group of antioxidants found in both humans and legumes, extracted from soybeans. While isoflavones do not show antioxidant activity in legumes, they serve various roles as protectants, attractants, and repellents. Because of their antioxidant characteristics, it is possible that isoflavones make a healthy contribution to the human diet.

Groceries and other retail stores sell products that contain soybeans in some form, and American and Oriental restaurants offer foods with soybean constituents. In addition, many products sold as dietary supplements or nutraceuticals in health food stores include soybeans.

Field peas (Pisum arvense and Pisum sativum). The green pea type of field pea became a food source in the sixteenth century. Field peas grow during the cool season and develop flowers and seeds as the days become longer. Field peas have a variety of uses, and production has increased worldwide. At the beginning of the twenty-first century, U.S. production was estimated at 200,000 hectares, and Canadian production exceeded that threefold. Major diseases include Ascochyta blight (Ascochytapisi and Ascochyta pinodella), bacterial blight (Pseudomonas pisi), and fusarium wilt (Fusarium oxysporum f. pisi). Significant insect pests are the pea weevil (Bruchus pisorum), the pea aphid (Illinoia pisi), and particularly the root knot nematode (Meloidogyne incognita). The wrinkled-seed types of field peas are canned in the immature stage, and the smooth-seed types are eaten as dried peas.

Field peas are usually grown as winter annuals in regions receiving 450 to 500 millimeters of rainfall annually. Generally, field peas perform best on well-drained soils with pH between 6.0 and 7.5. Nitrogen fertilization is not needed, but phosphorus, potassium, and sulfur are required (Muehlbauer, 1993).

The nutritional components of dried seeds are 10.6 percent water, 22.5 percent protein, 1 percent fat, 58.5 percent carbohydrate, and 4.4 percent fiber. Fresh green peas are about 74.3 percent water, 6.7 percent protein, 0.4 percent fat, 15.5 percent carbohydrate, and 2.2 percent fiber. These legumes are a major source of human dietary protein worldwide but are of minor importance in the United States. The seeds are consumed as a fresh vegetable and are canned, frozen, and dried. Field pea pods are also edible. Worldwide field pea plants are used for forage, hay, silage, and green manure (Purseglove, 1981).

Field beans (Phaeolus spp.). Brazil, the United States, Mexico, and Italy are the leading producers of field beans. In the United States the common field bean is grown primarily in New York, Michigan, and west of the Mississippi River. Suitable for a variety of soil types, beans are a warm season annual crop. The optimum temperature is 63–77°F (17–25°C), and the beans need 120 to 130 days without frost.

Field bean crops require fertilization with phosphorus and potassium, and zinc is often needed in residual amounts. Because beans are planted in warm soil after all danger of frost is past, planting dates vary from early April to early July according to geographic location. Dry beans are harvested after the pods turn yellow and prior to seed scattering (Martin and Leonard, 1967). Field beans are subject to a wide array of diseases, including bacterial blight (Xanthomonas phaseoli), anthracnose (Colletotrichum lindemuthianum), and common bean mosaic virus. Insect pests that cause substantial damage and loss are the bean weevil (Acanthoscelides obtectus) and the Mexican bean beetle (Ephilachna varivestris).

Rich in the amino acids lysine and tryptophane, field beans are one of the most important sources of human dietary protein. Dried adzuki beans (Phaseolus angularis), consumed in Japan and China in soups and cakes, are about 21 percent to 23 percent protein, 0.3 percent fat, and 65 percent carbohydrate. Mung beans (Phaseolus aureus) are about 9.7 percent water, 23.6 percent protein, 1.2 percent fat, 58.2 percent carbohydrate, and 3.3 percent fiber. The green mung bean pods are edible, and the fried seeds are popular in India (Purseglove, 1981). Flour from the seeds is used in Indian and Chinese foods, and in the United States grocery chains and restaurants offer mung bean sprouts. Rice beans (Phaseolus calcaratus) are consumed in India, Burma, Malaysia, China, Fiji, and the Philippines. The beans are usually boiled, and the young pods and leaves are also eaten. Rice beans are about 10.5 percent water, 21.7 percent protein, 0.6 percent fat, 58.1 percent carbohydrate, and 5.2 percent fiber.

Central Americans consume the green and dried seeds of the scarlet runner bean (Phaseolus coccineus). Lima or butter beans (Phaseolus lunatus) are eaten fresh, canned, or frozen in the United States. Dried lima beans are 12.6 percent water, 20.7 percent protein, 1.3 percent fat, 57.3 percent carbohydrate, and 4.3 percent fiber. However, the green beans contain about 66.5 percent water, 7.5 percent protein, 0.8 percent fat, 22.0 percent carbohydrate, and 1.5 percent fiber. The mature beans contain the glucoside phaseolutanin, which gives them their characteristic taste. Because the seeds contain hydrocyanic acid, the cooking water should be boiled and changed during preparation to dissipate the acid.

Black grams (Phaseolus mungo) are highly prized in vegetarian diets in India. They can be boiled or eaten whole, and they are ground into a flour used to make porridge or baked into bread and biscuits. The green pods are also edible. Dried black grams are about 9.7 percent water, 23.4 percent protein, 1.0 percent fat, 57.3 percent carbohydrate, and 3.8 percent fiber (Purseglove, 1981).

The most popular and most widely used beans are known as French beans, kidney beans, runner beans, snap beans, and string beans and are sold throughout the world in grocery stores and restaurants. These are the primary protein food in Latin American and tropical Africa, and in Europe and the United States they are grown for the immature pods, which are consumed fresh, canned, and frozen. The popular baked beans are made with any of these types of whole dried beans cooked with tomato sauce.

Winged bean (Psophocarpus tetragonolobus). The winged bean is a perennial vine that climbs by twining. Usually grown as annuals, the plants flower during short days. Scarifying winged bean seeds induces better germination. Seeds are planted anytime during the year and germinate within five to fifteen days. The plants tolerate various soil types, including heavy, poorly drained, riverbank, sandy, and infertile soils. Organic material in soil promotes successful winged bean growth; otherwise a small amount of mineral fertilizer is generally recommended. While few pests attack winged beans, geese and chickens consume the plants, and damage by cowpea aphids and root knot nematodes has been reported (Martin and Delpin, 1978).

Winged bean leaves, flowers, shoots, immature pods, mature dried seeds, and tubers, which are highly nutritious, are primarily consumed in Papua New Guinea, South Asia, and Southwest Asia. The young, tender pods, sliced or chopped, are eaten raw. The mature dried seeds are especially nutritious because of their high protein content, 30 to 42 percent. These mature seeds can be steamed, boiled, fried, roasted, or made into milk or tofu. The beans contain some antinutritional substances, thus the seeds should always be soaked overnight and then boiled in water until tender. Oil derived from winged beans contains behenic acid, linoleic acid, and tocopherols (vitamin E). Behenic acid reduces the digestibility of winged beans. Tocopherols are antioxidants that improve the utilization of vitamin A in the human body.

Winged bean tubers, which have a protein content of 8 to 20 percent, are eaten boiled, steamed, fried, or baked in Burma and Papua New Guinea. Winged bean sprouts and shoots are consumed raw or cooked. Usually only the top three leaves are eaten. The flowers, steamed or fried, taste similar to mushrooms. The seeds contain several antinutritional phytochemicals, such as trypsin and chymotrypsin inhibitors, amylase inhibitors, phytohemagglutinins, and cyanogenic glycosides. The seed inhibitor activity can be safely eliminated only by moist heat, that is, by soaking the seeds for ten hours and then boiling them for thirty minutes. Both vanilla-and chocolate-flavored milks have been produced from the seeds in Thailand. Scientists have developed snacks of the tubers sliced thin, fried, and salted or softened in sugar syrup. Immature winged bean pods are pickled in southern India (Martin and Delpin, 1978). Psophocarpus tetragonolobus lectin is derived from winged bean seeds and is used commercially in medical diagnostics.

Jicama (Pachyrhizus erosus andPachyrhizus tuberosus). Jicama is a tuberous legume commonly grown in Mexico on commercial farms and intercropped with maize and beans on smaller farms. It is also monocropped in Thailand, Malaysia, and Hawaii. Jicamas are usually grown from seeds, however, sprouted tubers are occasionally used. In Mexico tuber yields are highest when planted in March and harvested from September to November, and in Hawaii maximum tuber yields occur when planted in September or October and harvested five months later. Thus jicamas require a hot subtropical to tropical climate with moderate rainfall. They tolerate some drought but are sensitive to frost. They attract few pests but occasionally are attacked by the rose beetle (Adoretus versutus) and the bean common mosaic virus (Grum, 1990).

The edible portion of jicamas are about 87.1 percent water, 1.2 percent protein, 0.1 percent fat, 10.6 percent carbohydrate, and 0.7 percent fiber. The tubers are eaten raw or cooked. The young pods from Pachyrhizus erosus are prepared like French beans, but the mature seeds and roots of that plant contain a toxic substance known as rotenone. Young pods of Pachyrhizus tuberosus are avoided because they have irritant hairs (Purseglove, 1981).

Chickpea (Cicer arietinum). Chickpea is the major pulse crop in India, where production reaches 7 million hectares. In the United States, chickpeas are primarily grown in California, Washington, and Idaho. These legumes have a high phosphorus requirement, and both potassium and sulfur should be added if the soil is deficient in either. Chickpeas are adapted to dry conditions and generally flourish on well-drained soils of pH 6.0 to 7.5. The major chickpea pests include gram blight (Mycosphaerella rabiei), rust (Uromyces ciceris-arietini), wilt (Rhizoctonia bataticola and Fusarium orthoceras), and gram caterpillar (Heliothis armigera).

Chickpeas are important in India, where the dried seeds are boiled and the green pods and shoots are prepared in a variety of ways. Flour made from chickpeas is used in many Indian confections. The common chickpea, also called garbanzo bean, is used in the United States primarily in salads and as a vegetable side dish. Dried chickpeas are about 9.8 percent water, 17.1 percent protein, 5.3 percent fat, 61.2 percent carbohydrate, and 3.9 percent fiber (Purseglove, 1981).

Peanut (Arachis hypogaea). Peanuts, called groundnuts in other parts of the world, are one of the most important crops in the southern United States, primarily in Georgia, Texas, Oklahoma, North Carolina, Alabama, and Virginia. Other leading production countries include India, China, Nigeria, Senegal, Indonesia, and Brazil. An annual crop with a growing season from 1 May to 1 November in the United States, the peanut prefers sandy loam soils. Adequate soil moisture and high temperatures are necessities for seed germination and plant growth. Peanuts respond best when the pH is above 5. The American peanut is classified into three botanical types based on the shape of the nut and growth characteristics: Virginia (bunch and runner growth types), Spanish (bunch growth type), and Valencia (bunch growth type). Crop rotation is recommended because peanut yields are good following cotton or other nonleguminous crops, and applications of lime and potash usually increase yields. Peanuts suffer from cercospora leaf spots (Cercospora arachidicola and Cercospora personata), stem and peg rots (Sclerotium rolfsii), and tomato spotted wilt virus.

Peanuts are consumed by humans throughout the world as peanut butter, in candies, and as cooking oil. Peanut oil is about 53 percent oleic acid and 25 percent linoleic acid. The Virginia peanut is 38 percent to 47 percent oil, and the Spanish peanut is 47 percent to 50 percent oil. Shelled peanuts are about 5.4 percent water, 30.4 percent protein, 47.7 percent fat, 11.7 percent carbohydrate, and 2.5 percent fiber. The primary proteins in peanuts are arachin and conarachin, and peanuts are rich in vitamins B and E (Pattee and Young, 1982). Some people have allergenic reactions to certain types of peanuts. The peanut allergens designated as Ara h 1, Ara h 2, and Ara h 3 are glycoproteins with a molecular mass of 63 kilodaltons and are present in raw and roasted peanuts since they are heat stable and may be found in any peanut type. Peanut proteins, including arachin, conarachin, peanut agglutinin, and peanut phospholipase, can also be allergens. Other important phytochemicals in peanuts are protocatechuic acid, which has shown potential antioxidant and pesticidal qualities, and lecithin, which has shown antioxidant activity (Beckstrom-Sternberg and Duke, 1994). A lectin derived from peanuts is used commercially in medical diagnostics.

Cowpea(Vigna spp.). Cowpeas led U.S. legume production until about 1941, when they were replaced by soybeans, clovers, and other special-purpose legumes. Cowpeas are produced in California on a fairly large scale, and they are cultivated in Africa, southern Asia, and the Mediterranean region of Europe. A short-day, warm-weather crop, they should be planted in warm soil after all danger of frost has passed. However, severe drought will prevent seed formation. Cowpeas grow well in sandy or clay soils with good water drainage. The common black-eyed pea (Vigna unguiculata) is by far the most important cowpea variety.

Common diseases include cowpea wilt (Fusarium oxysporum var. tracheiphilum), cowpea root knot nematode (Meloidogyne spp.), charcoal rot (Macrophomina phaseoli), and viral diseases. The chief insect problems are the cowpea weevil (Callosobruchus maculatus) and the southern cowpea weevil or four-spotted bean weevil (Mylabris quadrimaculatus).

Legumes Cultivated for Phytochemicals

Jack beans (Canavalia ensiformis) are cultivated primarily for their phytochemicals. The ripe, dried seeds are about 11.0 percent water, 23.4 percent protein, 1.2 percent fat, 55.3 percent carbohydrate, and 4.9 percent fiber (Purseglove, 1981). Jack bean seeds are the only source of the lectin known as concanavaline-A, which is used in medical diagnostics. Lectins extracted from several other legumes, including sunn hemp (Crotalaria juncea), red kidney beans (Phaseolus vulgaris), and field peas (Pisum sativum), are used in medical diagnostics also. Guar seeds (Cyamopsis tetragonolobus) contain galactomannan gum, which is used in food additives; industrials; pharmaceuticals; confectionaries, including cereal, ice cream, and candy (Whistler and Hymowitz, 1979); and nutraceuticals, such as Ensure glucerna.

Kudzu (Pueraria spp.) produces isoflavones used in nutraceuticals for natural estrogen therapy, such as Estroven. A nutraceutical known as kudzu root is sold in powder form. Velvet bean (Mucuna pruriens) extract is marketed as an antiparkinsonian herbal supplement or nutraceutical. See Table 1 for additional legume phytochemicals.

Table 1

Minor legumes with special-purpose value
Name		Use
Scientific	Common	Agricultural	Bioactive	Phytochemical(Pharmacological)
Canavalia ensiformis (L.) DC.	Jack bean	Forage, green manure, pulse	Pesticide	Concanavalin-A (lectin)
				Canaline (allelochemic)
Crotalaria juncea (L.)	Sunn hemp	Paper, green manure	Bactericide, pesticide	Pectin (antidiabetic, antidiarrhetic, antitumor, antiulcer, cancer preventive)
Mucuna pruriens (L.) DC.	Velvet bean	Green manure	Bactericide, pesticide, viricide	Beta-sitosterol (anti-inflammatory, antileukemic, antitumor, cancer preventive, estrogenic)
				Gallic acid (antioxidant, antiseptic, antiviral, cancer preventive)
				Lecithin (anti-Alzheimeran, hepatoprotective)
Rhynchosia minima (L.) DC.	Snout bean	Forage	Fungicide, pesticide, viricide	Gallic acid (see above)
				Protocatechuic acid (antiasthmatic, antioxidant)
Senna occidentalis (L.) Link	Coffee senna		Bactericide, pesticide, viricide	Tannin (antidiarrhetic, antioxidant, antiviral, cancer preventive)
Tephrosia purpurea (L.) Pers.			Pesticide	Rutin (antidiabetic, anti-inflammatory, antioxidant, antitumor, antiviral, cancer preventive)

Legumes Cultivated for Animal Food

Legume species used for forage include Aeschynomene, Desmodium, Leucaena, Macroptilium, Neonotonia, Stylosanthes, Desmanthus, Macrotyloma, Sesbania, and Trifolium. Several species, including Desmanthus virgatus, Stylosanthes scabra, and Stylosanthes guianensis, have been tested in the southeastern United States for possible forage production. Stylosanthes hamata, Stylosanthes humilis, Macroptilium atropurpureum, Macroptilium bracteatum, Neonotonia wightii, and Lotononis bainesii are grown successfully as pasture legumes in Australia and show potential for use in the United States (Morris, 1997).

Other Uses for Legumes

Several legumes have multiple uses as human foods, animal feeds, ornamentals, cover crops, green manure, and erosion control plants. Minor legumes used primarily for cover crops, forage, and green manure worldwide include calopo (Calopogonium mucunoides), centro (Centrosema pubescens), and tropical kudzu (Pueraria phaseoloides) (Morris, 1997).

Indigofera arrecta was once cultivated in India for indigo dye, but it declined significantly with synthetic dye production. In Central Africa, however, indigo dye derived from the plant is still used. Dhaincha (Sesbania bispinosa) produces galactomannan gum and is grown also for soil improvement, fiber for paper pulp, fodder, and its ornamental qualities. Lead trees (Leucaena leucocephala), similar in growth to mimosa trees, are used for paper products and as cover crops, fodder, pastures, green manure, and ornamentals (Morris, 1997). Other legumes are important in reclamation of mined soils, polluted soils, deforested areas, and soils with poor nutritional conditions (Morris, 1997).

Legume Traditions

The expression "blackball" comes from the ancient Greek and Roman practice of using beans for voting. A white bean signifies acceptance, while a black bean means rejection. The black-eyed pea is eaten on New Year's Day in the southern United States to bring good luck for the coming year.

The Navaho-Ramah Indian tribe used an annual clover known as Trifolium dubium as a ceremonial medicine. For a dermatological remedy the Iroquois used a wild bean known as Strophostyles helvola, and the Pawnees used spider bean (Desmodium illinoensis). Bush clover or rabbit foot (Lespedeza capitata) was an antidote in the Fox tribe and an analgesic for the Omahas and Poncas. The Cherokees chewed tickseed or trefoil (Desmodiumperplexum) roots for sore gums and mouths. The Mohegans made a blood purifier from rattle box (Crotalaria sagittalis) root, and the Delawares treated venereal disease with rattle box root (Beckstrom-Sternberg, Duke, and Wain, 1994). See Table 2 for additional ethnobotanical and multicultural uses of legumes.

Table 2

Ethnobotanical uses of minor legumes
Scientific name	Common name	Uses	Countries
Canavalia ensiformis (L.) DC.	Jack bean	Kidney and tonic	China
Clitoria ternatea (L.)	Butterfly pea	Arthritis	Philippines
		Scorpion bite	Sudan
		Laxative	Samoa
		Snake bite	Iraq
Crotalaria juncea (L.)	Sunn hemp	Psoriasis	Iraq
Crotalaria retusa (L.)	Rattle box	Fever	Java
Desmodium adscendens (Sw.) DC.	Tick clover	Bronchitis, colic, ringworms, wound	Africa
		Cough	Cameroon
		Laxative	Ghana
Desmodium gangeticum (L.) DC.		Dysentery, fever, tonic	India
Indigofera tinctoria (L.)	Common indigo	Fever, inflammation, laryngitis, mumps, scabies, swelling, dysentery	China
		Antiseptic, fever	Turkey
Leucaena leucocephala (Lam.) de Wit	Lead tree	Fever, typhoid	Bahamas
		Laxative	Dominican Republic
Mucuna pruriens (L.) DC.	Velvet bean	Scorpion antidote, asthma, snake bite, cancer, coffee, cough, diarrhea, mumps, ringworms, syphilis, tumor	India, Venezuela, Mexico
Psophocarpus tetragonolobus (L.) DC.	Wing bean	Boil, tumor	Java
Tephrosia candida DC.	White tephrosia	Insecticide, piscicide	India, Java
Tephrosia cinerea (L.) Pers.		Fever, piscicide, venereal, tumor	Mexico, Guiana, Brazil, Venezuela
Tephrosia purpurea (L.) Pers.		Colic, piscicide	Sudan, Guiana, Mexico
Tephrosia vogelii Hook. f.	Fish poison bean	Insecticide, insect repellant, piscicide	India, Tanzania, Sudan, Africa

Uses for Legumes

Senna occidentalis—Potential bactericidal, pesticidal, and viricidal plant. It also contains tannin, which is an antidiarrhetic, an antioxidant, and an antiviral agent and has cancer preventive potential.

Crotalaria juncea—Sunn hemp, known as a multiple-use small-tree crop. It is used in paper making and as green manure and has bactericidal qualities. Sunn hemp contains pectin, which has antidiabetic, antidiarrhetic, antitumor, antiulcer, and cancer preventive potential. Sunn hemp has been used in Iraq to treat psoriasis.

Mucuna pruriens—Velvet bean, a green manure crop and a nutraceutical in the United States. The seeds contain L-dopa, which is used in the treatment of Parkinson's disease, beta-sitosterol, a potential anti-inflammatory, antileukemic, antitumor, cancer preventive, and estrogenic agent; gallic acid, a potential antioxidant, antiseptic, antiviral agent, and cancer preventive; and lecithin, a potential Alzheimer's preventive. Velvet bean is also used in India, Venezuela, and Mexico to treat asthma, snake bites, cancer, coughs, diarrhea, mumps, ringworm, syphilis, and tumors and as a scorpion antidote.

Bibliography

Beckstrom-Sternberg, Stephen M., and James A. Duke. "The Phytochemical Database." Data version July 1994. Available at http://ars-genome.cornell.edu/cgi-bin/WebAce/webace?db=phytochemdb.

Beckstrom-Sternberg, Stephen M., James A. Duke, and K. K. Wain. "The Ethnobotany Database." Data version July 1994. Available at http://ars-genome.cornell.edu/cgi-bin/WebAce/webace?db=ethnobotdb.

Bisby, Frank A., James L. Zarucchi, B. D. Schrire, Y. R. Roskov, and Richard J. White, eds. International Legume Database and Information Service. 5th ed. Reading, U.K.: ILDIS, 2000.

"Ecology." In The Columbia Encyclopedia, edited by Paul Lagassé. 6th ed. New York: Columbia University Press, 2000.

Grum, Mikkel. Breeding Pachyrhizus Rich. Ex DC.: A Review of Goals and Methods. Copenhagen, Denmark: Royal Veterinary and Agricultural University, Department of Crop Husbandry and Plant Breeding, 1990.

Hymowitz, Theodore. "Grain Legumes." In Advances in New Crops, edited by Jules Janick and James E. Simon. Portland, Oreg.: Timber Press, 1990.

Martin, Franklin W. Soybean. Fort Myers, Fla.: Educational Concerns for Hunger Organization, ECHO Technical Note, 1988.

Martin, Franklin W., and Herminio Delpin. Vegetables for the Hot, Humid Tropics. Part 1: The Winged Bean, "Psophocarpus Tetragonolobus." New Orleans: Department of Agriculture, Science, and Education Administration, 1978.

Martin, John H., and Warren H. Leonard. "Legumes." In Principles of Field Crop Production. 2d ed. New York: Macmillan, 1967.

Morris, John Bradley. "Special-Purpose Legume Genetic Resources Conserved for Agricultural, Industrial, and Pharmaceutical Use." Economic Botany 51, no. 3 (July–September 1997): 251–263.

Muehlbauer, Fred J. "Food and Grain Legumes." In New Crops, edited by Jules Janick and James E. Simon. New York: Wiley, 1993.

Pattee, Harold E., and Clyde T. Young, eds. Peanut Science and Technology. Yoakum, Tex.: American Peanut Research and Education Society, 1982.

Purseglove, J. W. "Leguminosae." In Tropical Crops: Dicotyledons. 2 vols. New York: Wiley, 1987.

Whistler, Roy L., and Theodore Hymowitz. Guar: Agronomy, Production, Industrial Use, and Nutrition. West Lafayette, Ind.: Purdue University Press, 1979.

—Brad Morris

A member of the legume or pea family (Leguminosae, formerly Fabaceae), a group that includes clovers, beans, wisteria, and mimosa.

1. the pod or fruit of a leguminous plant, such as peas and beans.
2. a leguminous plant, i.e. a member of the family Leguminosae.

• l. bloat — frothy ruminal tympany in cattle grazing clover or lucerne.

(ləgyōōmz')
n

Any plant belonging to the order Fabales and family Leguminosae. Examples of legumes are beans, peas, and lentils.

For a list of words related to legume, see:

• Botany and Plant Parts - legume: any of the family of herbaceous plants, shrubs, and vines having compound leaves, clusters of flowers, and fruit in form of pod
• Types of Food - legume: pod or seed of certain herbs or shrubs
• Vegetables, Legumes, and Fungi - legume: pod or seed of certain herbs or shrubs

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Dansk (Danish)
n. - bælgplante, bælgfrugt, bælg

Nederlands (Dutch)
peulvrucht, groente (op menu)

Français (French)
n. - légumineuse, fruit comestible d'une légumineuse

Deutsch (German)
n. - Hülsenfrucht

Ελληνική (Greek)
n. - (φυτολ.) όσπριο

Italiano (Italian)
legume

Português (Portuguese)
n. - legume

Русский (Russian)
растение семейства бобовых, фасоль, горошек

Español (Spanish)
n. - legumbre

Svenska (Swedish)
n. - balja, skidfrukt, legymer, grönsaker, ärtväxter, foderväxter

中文（简体）(Chinese (Simplified))
豆类, 豆荚

中文（繁體）(Chinese (Traditional))
n. - 豆類, 豆莢

한국어 (Korean)
n. - 콩, 콩과 식물의 꼬투리

日本語 (Japanese)
n. - マメ科植物, 豆果, マメ科の植物, マメ

العربيه (Arabic)
‏(الاسم) بقول كالحمص والفول, كل صنف من الخضر, نبات بقلي‏

עברית (Hebrew)
n. - ‮קטנית‬