Phaseolus vulgaris

Phaseolus vulgaris
A flat-podded variety of the common bean
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Rosids
Order:	Fabales
Family:	Fabaceae
Subfamily:	Faboideae
Tribe:	Phaseoleae
Subtribe:	Phaseolinae
Genus:	Phaseolus
Species:	P. vulgaris
Binomial name
Phaseolus vulgaris L.
Synonyms[1]
Phaseolus aborigineus Burkart Phaseolus communis Pritz. Phaseolus compressus DC. Phaseolus esculentus Salisb. Phaseolus nanus L.

Blossoms of the common bean

Bean cultivars illustrated in Les plantes potagères (1891 Vilmorin-Andrieux et Cie catalog)

Diversity in dry common beans

Phaseolus vulgaris, the common bean^[2] (also known as the string bean, field bean, flageolet bean, French bean, garden bean, green bean, haricot bean, pop bean, or snap bean),^[3] is a herbaceous annual plant grown worldwide for its edible dry seed (known as just "beans") or unripe fruit (green beans). Raw or undercooked beans contain the toxin phytohaemagglutinin. Its leaf is also occasionally used as a vegetable and the straw as fodder. Its botanical classification, along with other Phaseolus species, is as a member of the legume family Fabaceae, most of whose members acquire the nitrogen they require through an association with rhizobia, a species of nitrogen-fixing bacteria.

The common bean is a highly variable species that has a long history of cultivation. All wild members of the species have a climbing habit,^[4] but many cultivars are classified as "bush beans" or "pole beans", depending on their style of growth. These include the kidney bean, the navy bean, the pinto bean, and the wax bean.^[3] The other major types of commercially grown bean are the runner bean (Phaseolus coccineus) and the broad bean (Vicia faba).

Beans are grown in every continent except Antarctica. Brazil and India are the largest producers of dry beans, while China produces, by far, the largest quantity of green beans. Worldwide, 23 million tonnes of dry common beans and 17.1 million tonnes of green beans were grown in 2010.

The wild P. vulgaris was native to the Americas and was domesticated separately in Mesoamerica and in the southern Andes region, giving the domesticated bean two gene pools which remain separate to this day.^[5] Along with squash and maize (corn), beans are one of the "Three Sisters" central to indigenous North American agriculture.

Description

The common bean is a highly variable species with a long history. Bush varieties form erect bushes 20–60 cm (8–20 in) tall, while pole or running varieties form vines 2–3 m (7–10 ft) long. All varieties bear alternate, green or purple leaves, which are divided into three oval, smooth-edged leaflets, each 6–15 cm (2–6 in) long and 3–11 cm (1–4 in) wide. The white, pink, or purple flowers are about 1 cm long, and they give way to pods 8–20 cm (3–8 in) long and 1–1.5 cm wide. These may be green, yellow, black, or purple in color, each containing 4–6 beans. The beans are smooth, plump, kidney-shaped, up to 1.5 cm long, range widely in color, and are often mottled in two or more colors.

Dry beans

Similar to other beans, the common bean is high in starch, protein, and dietary fiber, and is an excellent source of iron, potassium, selenium, molybdenum, thiamine, vitamin B₆, and folate.

Dry beans will keep indefinitely if stored in a cool, dry place, but as time passes, their nutritive value and flavor degrade and cooking times lengthen. Dried beans are almost always cooked by boiling, often after being soaked in water for several hours. While the soaking is not strictly necessary, it shortens cooking time and results in more evenly textured beans. In addition, soaking beans removes 5 to 10% of the gas-producing sugars that can cause flatulence for some people.^[6] The methods include simple overnight soaking and the power soak method in which beans are boiled for three minutes and then set aside for 2–4 hours. Before cooking, the soaking water is drained off and discarded. Dry common beans take longer to cook than most pulses: cooking times vary from one to four hours, but are substantially reduced with pressure cooking.

In Mexico, Central America, and South America, the traditional spice used with beans is epazote, which is also said to aid digestion. In East Asia, a type of seaweed, kombu, is added to beans as they cook for the same purpose. Salt, sugar, and acidic foods such as tomatoes may harden uncooked beans, resulting in seasoned beans at the expense of slightly longer cooking times.

Dry beans may also be bought cooked and canned as refried beans, or whole with water, salt, and sometimes sugar.

Green beans and wax beans

The three commonly known types of green beans are: string or snap beans, which may be round or have a flat pod; stringless or French beans, which lack a tough, fibrous "string" running along the length of the pod; and runner beans, which belong to a separate species, Phaseolus coccineus. Green beans may have a purple rather than green pod, which changes to green when cooked.^[7] Wax beans are P. vulgaris beans that have a yellow^[4] or white pod. Wax bean cultivars are commonly grown;^[4] the plants are often of the bush form.^[4]

Compared to dry beans, green and wax beans provide less starch and protein and more vitamin A and vitamin C. Green beans and wax beans are often steamed, boiled, stir-fried, or baked in casseroles.

Shelling beans

Shell, shelled, or shelling beans are beans removed from their pods before being cooked or dried. Common beans can be used as shell beans, but the term also refers to other species of beans whose pods are not typically eaten, such as lima beans, soybeans, peas, and fava beans. Fresh shell beans are nutritionally similar to dry beans, but are prepared more like a vegetable, often being steamed, fried, or made into soups.

Popping beans

The nuña is an Andean subspecies, P. v. subsp. nunas (formerly P. vulgaris Nuñas group), with round, multicolored seeds that resemble pigeon eggs. When cooked on high heat, the bean explodes, exposing the inner part, in the manner of popcorn and other puffed grains.

Toxicity

The toxic compound phytohaemagglutinin, a lectin, is present in many common bean varieties, but is especially concentrated in red kidney beans. White kidney beans contain about a third as much toxin as the red variety; broad beans (Vicia faba) contain 5 to 10% as much as red kidney beans.^[8]

Phytohaemagglutinin can be deactivated by cooking beans for ten minutes at boiling point (100 °C, 212 °F). Insufficient cooking, such as in a slow cooker at 80 °C/ 176 °F, however, can increase the toxicity up to fivefold.^[9] To safely cook the beans, the U.S Food and Drug Administration recommends boiling for 30 minutes to ensure they reach a sufficient temperature for long enough to completely destroy the toxin.^[10] For dry beans, the FDA also recommends an initial soak of at least 5 hours in water which should then be discarded.^[8] Outbreaks of poisoning have been associated with cooking kidney beans in slow cookers.^[8]

The primary symptoms of phytohaemagglutinin poisoning are nausea, vomiting, and diarrhea. Onset is from one to three hours after consumption of improperly prepared beans, and symptoms typically resolve within a few hours.^[8] Consumption of as few as four or five raw, soaked kidney beans can cause symptoms.^[8] Canned red kidney beans, though, are safe to use immediately.^[11][12][13]

Beans are high in purines, which are metabolized to uric acid. Uric acid is not a toxin as such, but may promote the development or exacerbation of gout. So people with gout have been advised in the past to limit their consumption of beans.^[14] However, more recent research has questioned this association, finding that moderate intake of purine-rich foods is not associated with increased risk of gout.^[15]

Cultivars/varieties

Many well-known bean cultivars/varieties belong to this species, and none of the lists below is in any way exhaustive. Both bush and running (pole) cultivars/varieties exist. The colors and shapes of pods and seeds vary over a wide range.

Name	Image	Description
Appaloosa		Front portion of the bean is ivory colored; the other end is speckled with purple and mocha. The bean is named after the Appaloosa ponies of the Nez Perce tribe. The seed was cultivated near the Palouse River in Eastern Washington and Northern Idaho.
Black turtle		The black turtle bean has small, shiny black seeds. It is especially popular in Latin American cuisine.
Calypso		Calypso beans are half black, half white, with one or two black dots in the white area. When young, the pods can be harvested as a green bean. But when full-grown, they are used as a bean for drying.
Cranberry		Cranberry beans originated in Colombia as the cargamanto bean. Borlotti or Roman beans are a variety of cranberry bean bred in Italy to have a thicker skin. They are much used in Mediterranean cuisine.
Dragon tongue		Dragon tongue bean is young green bean of cranberry bean, pinto bean. It is a flavorful, juicy bean whose seeds are encased in a buffed colorful pod with mottled burgundy patterns throughout the shell's surface. The shelled beans are pale pistachio green in color, their size, petite, and their shape, ovate and slightly curved.[16]
Flageolet		Flageolet beans are often eaten in France. The seeds are small, light green, and kidney-shaped. The texture is firm yet creamy if shelled and cooked when fresh but semidry.
Kidney		Kidney beans, also known as red beans, are named for their visual resemblance in shape and color to kidneys. They are sometimes used in chili con carne, and are an integral part of the cuisine in northern regions of India. They are also used in New Orleans and much of southern Louisiana for the Monday Creole dish of red beans and rice.
Pea		A type of P. vulgaris called pea bean has been recorded in Britain since the 16th century.[17] In the US, the name "pea bean" is also used to describe small white beans, and the same name is used for Vigna unguiculata subsp. sesquipedalis, also called yard-long bean and cowpea.[18] The seeds of the British pea bean are bicolored red-brown and white. The plants are a typical climbing bean. The beans are either eaten in the pod like French beans or they may be harvested when mature and eaten as other dried beans.[19]
Pink		Pink beans are small, pale pink, oval-shaped beans also known by the Spanish name habichuelas rosadas.[20] The Santa Maria pinquito (Spanglish = pink and small), is commercially grown on the mesas above Santa Maria, California, and is a necessary ingredient in Santa Maria-style barbecue.
Rattlesnake		A medium-sized, oblong bean with light brown seeds striped with brown markings. Named for the snake-like manner in which their pods coil around the vine.[21]
Pinto		Pinto beans are named for their mottled skin. They are the most common bean in the United States[22] and northwestern Mexico,[23] and are most often eaten whole in broth or mashed and refried. Either whole or mashed, they are a common filling for burritos. The young pods may also be harvested and cooked as green pinto beans.
White		Navy beans or haricot beans are particularly popular in the United Kingdom and the United States. Other white beans include cannellini, a popular variety in central and southern Italy that is related to the kidney bean. White beans are the most abundant plant-based source of phosphatidylserine known.[24]
Yellow		'Sinaloa Azufrado', 'Sulphur', 'Mayocoba', and 'Peruano' (also called canary) are types of yellow beans. Peruano beans are small, oval, yellow beans about 1/2 in (1 cm) long with a thin skin. They have a creamy texture when cooked. Despite the name ('Peruvian beans' in Spanish), they are native to Mexico. Yellow beans are uncommon in the United States due to a controversial patent issued in 1999 to John Proctor, who selected and named a strain of yellow bean from seeds he brought back from Mexico. U.S. Patent No. 5,894,079 (the Enola or yellow bean patent) granted POD-NERS, LLC., exclusive right to import and sell yellow beans in the United States from 1999 through 2008, when the patent was rejected after reexamination.[25][26]
Tongue of Fire		Tongue of Fire (also known as Horto)[27] has ivory white pods with red streaks that look like flames. The bean stalks grow close together, require plenty of sun and form large roundish pods. Original seed was reportedly from Tierra del Fuego on the tip of South America, sent to Italy and spread through southern Europe.

Production

Climbing beans growing in DR Congo

Bush bean field in Laos

In 2010, total world production of dry beans was 23 million metric tons, harvested from over 30 million hectares.^[28] World production of green beans in 2010 was 17.7 million ton, harvested from 15.1 million hectares.^[28]

Top ten dry bean producers (million metric tons), 2010  India 4.87  Brazil 3.20  Myanmar 3.03  China 1.53  United States 1.44  Mexico 1.16  Tanzania 0.95  Uganda 0.46  Kenya 0.39  Argentina 0.34 World Total 23.23

Top ten green bean producers (million metric tons), 2010  China 13.03  Indonesia 0.88  Turkey 0.59  India 0.58  Thailand 0.30  Egypt 0.27  Morocco 0.20  Italy 0.18  Spain 0.17  Mexico 0.10 World Total 17.65

Other uses

Bean leaves have been used to trap bedbugs in houses.^[29] Microscopic hairs (trichomes) on the bean leaves entrap the insects.^[29]

From ancient times, beans were used as device in various methods of divination. Fortune-telling using beans is called favomancy.

See also

Wikimedia Commons has media related to Phaseolus vulgaris.

References

Further reading

• Meers, E.; et al. (2007). "Phytoavailability assessment of heavy metals in soils by single extractions and accumulation by Phaseolus vulgaris". Environmental and Experimental Botany. 60 (3): 385–396. doi:10.1016/j.envexpbot.2006.12.010. 

External links

• Fact sheet with nutritional information on pinto beans at WHFoods.org.
• Introducing flageolet beans on the Multilingual Multiscript Plantname Database site.
• Plant lectins.
• USAID fact sheet with nutritional information on black beans.
• "US Department of Agriculture Commodity Fact Sheet for Pinto Beans" (PDF). fns.usda.gov. Retrieved 2013-01-25. 
• Dry bean nutritional comparison chart.
• Crops for the Future: Popping beans (Phaseolus vulgaris)
• A Bean Collector Window, an extensive gallery of bean varieties