Vigna unguiculata (L.) Walp.

Extinction risk predictions for the world's flowering plants to support their conservation (2024). Bachman, S.P., Brown, M.J.M., Leão, T.C.C., Lughadha, E.N., Walker, B.E. https://nph.onlinelibrary.wiley.com/doi/full/10.1111/nph.19592

Conservation

Predicted extinction risk: not threatened. Confidence: confident

Kew Species Profiles

General Description

Vigna unguiculata is a leguminous crop plant belonging to the same genus as bambara groundnut. It was first domesticated in West Africa 5,000-6,000 years ago and today is grown commercially in over 33 countries. It is a hardy crop which thrives in sandy soils and is relatively tolerant of drought. It is considered the most important pulse crop in the savannahs of West and Central Africa where it is also cultivated as a vegetable and to feed livestock.

Species Profile

Geography and distribution

Cowpea originated in Africa and today the greatest diversity of cowpea can be found in West Africa in the savanna regions of Burkino Faso, Ghana, Togo, Benin, Niger, Nigeria, and Cameroon. Cowpea was introduced to Europe, probably around 300 BC and to India 200 BC. The Spanish introduced cowpea to tropical America in the 17th century and the crop is grown widely in the United States, the Caribbean region and Brazil.

As a result of human selection, cowpea has diversified into two cultivar groups: 

Sesquipedalis - has long pods and is used as a vegetableBiflora - is cultivated for its pods, dry seeds and for fodder Description

Overview: Vigna unguiculata can be either an annual (completing its lifecycle in one year) or a perennial (living for several years) herb. Some types are erect and trailing and other are climbing herbs up to 4 metres long. The plant has a well-developed taproot with many lateral roots extending from it. 

Leaves:  Positioned alternately along the stem and composed of three leaflets. The petiole, the appendage which holds the leaf is up to 15 cm long, and in some cases 25 cm long, grooved above and swollen at the base. 

Flowers: The flowers which are pink to purple (sometimes white within the var. unguiculata cultivar group Melanophthalmus) are clustered towards the top of an unbranched axis (known as a raceme). The flowers are papilionaceous, typical of species belonging to the subfamily Papilionoideae, and resemble, for example, the pea flower. Each flower has 10 stamens (male reproductive organs), nine of which are fused together and one free. The ovary (female reproductive organ) is 1.5 cm long. 

Fruit: A cylindrical seed pod 8-30 cm long (in some cases 120 cm long), is pale brown when ripe and bears 8-30 seeds. The seeds are oblong to globose (spherical) 0.5-1 cm long and can be black, brown, pink or white. The hilium (the scar left on the seed from its attachment point to the placenta) is oblong, covered with a white tissue with a blackish rim. 

Uses

Cowpea is a crop cultivated mainly for its seeds, which can be cooked and eaten alone or mixed in with other vegetables and spices to produce a nutritious bean soup. 

Cowpea is eaten in large parts of Africa and in many areas it is the preferred pulse. In West Africa, cowpea seeds are ground into flour and mixed with onions and spices to make cakes which are either deep dried ('akara balls') or steamed ('moin moin') for a delicious snack. Cowpea flour can also be processed into crackers and baby foods, as is the case in Senegal, Ghana and Benin. In the United States, green seeds are sometimes roasted like peanuts.

Besides the seeds, the leaves and pods of cowpea are eaten as vegetables which can be served boiled or fried. Many people dry the leaves in the sun to preserve them so that they can be eaten during the dry season when food is scarce. The best leaves to use are those picked towards the end of the season, because these tend to grow under conditions of stress and are generally tastier. 

Cooked cowpea pods are more typical of Asian cuisine than African cuisine. In some parts of Africa, such as Ethiopia and Sudan, the roots are occasionally eaten. 

The high protein content of cowpea makes it an excellent fodder crop. Cowpea is cultivated for fodder in West Africa, Asia, and Australia; it is used for grazing or mixed in with dry cereals for animal feed.

In Nigeria some varieties of cowpea are cultivated for their strong fibre which is used to make fishing gear as well as to produce good quality paper. In the United States cowpea is grown for green manure. The dry seeds also make a good alternative to coffee.

Various parts of the cowpea are used medicinally. The leaves and seeds are applied to skin infections as a poultice, the leaves are chewed to relieve toothache and powdered carbonized seeds are applied to insect stings. The roots are used as treatment for epilepsy, chest pain, constipation and as an antidote to snakebites.

Its ability to fix nitrogen from the air makes cowpea a good fertiliser for the soil. In rice farming, farmers grow cowpea either before or after the rice crop, as this is found to increase the food production from the land area.

In folklore, cowpea is used in sacrifices by the Hausa and Yoruba tribes to drive away evil and to pacify the spirits of sickly children. 

Crop wild relatives of cowpea

The Millennium Seed Bank and the Global Crop Diversity Trust are engaged in a ten-year project, called 'Adapting Agriculture to Climate Change'. The project aims to protect, collect and prepare the wild relatives of 29 key food crops, including cowpea, so that they are available to pre-breeders for the development of new varieties that are more resilient to the effects of climate change.

Millennium Seed Bank: Seed storage

The Millennium Seed Bank Partnership aims to save plants worldwide, focusing on those plants which are under threat and those which are of most use in the future. Once seeds have been collected they are dried, packaged and stored at -20°C in our seed bank vault.

Description of seeds: Average 1,000 seed weight = 103 g

Number of seed collections stored in the Millennium Seed Bank: Five

Seed storage behaviour: Orthodox (the seeds of this plant can be dried to low moisture contents without significantly reducing their viability. This means they are suitable for long-term frozen storage such as at the MSB)

Germination testing: Successful

This species at Kew

Pressed and dried specimens of cowpea are held in Kew's Herbarium, where they are available to researchers by appointment. Details and images of some of these specimens can be seen online in Kew's Herbarium Catalogue. 

Distribution

Brazil, Burkina Faso, Cameroon, Niger, USA

Ecology

Wild types grow well in savannah vegetation, in disturbed localities or as a weed at up to 1,500m altitude. It can also be found in sandy areas, coastlines, woodland, forest edges or swampy areas.

Conservation

Widespread in cultivation.

Bernal, R., Gradstein, S.R. & Celis, M. (eds.). 2015. Catálogo de plantas y líquenes de Colombia. Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Bogotá. http://catalogoplantasdecolombia.unal.edu.co

Distribution

Cultivada en Colombia; Alt. 70 - 1000 m.; Llanura del Caribe, Orinoquia, Valle del Cauca.

Morphology General Habit

Trepadora

Leguminosae, B. Mackinder, R. Pasquet, R. Polhill and B. Verdcourt. Flora Zambesiaca 3:5. 2001

Morphology General Habit

Annual or perennial erect trailing or climbing herb, 0.5–3 m long.

Morphology Stem

Stem striate, glabrous, scabrous, pubescent or hairy.

Morphology Leaves Leaflets

Leaflets 3, 1.5–16.5 × 1–12.5 cm, ovate, rhombic or lanceolate to linear, the laterals oblique, all entire or terminal leaflets subhastate to deeply 3-lobed at the base and laterals lobed on the outer margin, shortly acuminate or subacute and mucronulate, acute to rounded at the base, glabrous to pubescent on both surfaces; petiole 1.5–13 cm long; rhachis 0.6–2.5 cm long; stipules submedifixed, constricted at the point of attachment, multinerved, upper part lanceolate, 6–20 mm long, spur narrower, 2–6 mm long.

Morphology Reproductive morphology Inflorescences

Peduncle 2–36 cm long.

Morphology Reproductive morphology Flowers

Flower pink to purple, rarely white (mainly within var. unguiculata cultivar-group Melanophthalmus), 15–33 mm long; pedicel 1–3 mm long, not expanding as the pod matures; bracteoles 3–6 mm long, spathulate or lanceolate, 1–3-nerved.

Morphology Reproductive morphology Flowers Calyx

Calyx glabrous or pubescent; tube 2–5.5 mm long; lobes subequal, ciliolate, the upper pair joined for about half their length to form a broad lobe bifid at the apex or only at the base.

Morphology Reproductive morphology Flowers Corolla

Standard with 2 parallel widely spaced appendages.

Morphology Reproductive morphology Fruits

Pod 8–10 × 2.5–5 mm (except within cultivated races), linear-cylindrical, glabrous, scabrous, or pubescent.

Morphology Reproductive morphology Seeds

Seed 4–6.5 × 2–4.5 mm (except within cultivated races); hilum one third to half the longest dimension, excentric; rim aril slightly developed.

Distribution

Biogeografic region: Caribbean, Orinoquia. Elevation range: 70–1000 m a.s.l. Cultivated in Colombia. Naturalised in Colombia. Colombian departments: Amazonas, Antioquia, Atlántico, Bolívar, Caquetá, Casanare, Cesar, Córdoba, Cundinamarca, La Guajira, Magdalena, Santander, Valle del Cauca.

Habit

Climbing.

Ecology

Habitat according IUCN Habitats Classification: forest and woodland, savanna, shrubland, wetlands (inland), desert, artificial - terrestrial.

Papilionaceae, Hutchinson and Dalziel. Flora of West Tropical Africa 1:2. 1958

Morphology General Habit

Stems annual but often stout, subglabrous, twining

Ecology

On trees, etc.

Morphology Reproductive morphology Flowers

Flowers white and mauve-tinged or pink or yellow.

Leguminosae, J. B. Gillett, R. M. Polhill & B. Verdcourt. Flora of Tropical East Africa. 1971

Morphology General Habit

Annual or perennial erect trailing or climbing herb, 1–3 m. long.

Morphology Stem

Stems striate, glabrous or slightly hairy particularly near the petiole-bases, sometimes with minute stiff hook-like hairs.

Morphology Leaves

Leaflets 3, ovate, rhomboid or lanceolate, the laterals oblique, 1·5–16·5 cm. long, 1–12·5 cm. wide, all entire or terminal leaflets subhastate to 3-lobed at the base and laterals lobed on the outer margin, shortly acuminate or subacute and mucronulate, acute to rounded at the base, glabrous or sparsely pubescent on both surfaces; petioles 1·5–13 cm. long; rhachis 0·6–2·5 cm. long; petiolules 2–5 mm. long; stipules submedifixed, constricted at the point of attachment, upper part lanceolate, 0·6–2 cm. long, spur narrower, 2–6 mm. long.

Morphology Reproductive morphology Inflorescences

Inflorescences axillary, few-several-flowered; rhachis 0·5–4(–5) cm. long; peduncle 2–36 cm. long, usually minutely uncinulate pubescent towards the apex; pedicels 1–2(–4) mm. long; bracts deciduous, lanceolate, 3–5 mm. long; bracteoles ± persistent, spathulate, 3–5 mm. long.

Morphology Reproductive morphology Flowers Calyx

Calyx glabrous; tube 3–5·5 mm. long; lobes triangular-lanceolate, 2·5–14 mm. long, acuminate, ciliolate; upper pair joined for about half their length or only at the base.

Morphology Reproductive morphology Flowers Corolla

Standard white, greenish, yellow or lilac-purple, paler outside, round, 1·2–3·3 cm. long, 1–3·2(–4) cm. wide, rounded or emarginate, glabrous; wings blue to purple; keel usually white or pale, not twisted.

Morphology Reproductive morphology Fruits

Pods erect or eventually hanging in cultivated forms, linear-cylindrical, 5·5–10(–90 in some cultivated races) cm. long, 3–11 mm. wide, glabrous or minutely verruculose.

Morphology Reproductive morphology Seeds

Seeds white to dark red or black, often mottled with black or brown, oblong or reniform, longest dimension 3·5–5(–12) mm., shorter dimension 2–3·5(–6·5) mm., 2·2(–4·5) mm. thick; hilum one-third to half the longest dimension, eccentric; rim-aril slightly developed.

Distribution

Throughout tropical Africa, where doubtless it originated, but now widely cultivated in some form or other throughout warmer parts of the world

International Legume Database and Information Service

Conservation

Not Threatened

Ecology

Africa: Zambezian woodland, Sudanian bushland and thicket, Somalia-Masai woodland, Sudanian grasslands, Somalia-Masai grasslands, Somalia-Masai bushland and thicket, Sudanian woodland, Zambezian bushland and thicket, Cultivated, Zambezian grassland

Morphology General Habit

Annual/Perennial, Climbing/Not climbing, Herb

Vernacular

Antaka, Asparagus Bean, Avokondrana, Barbati, Black Eye Pea, Boeme, Catjang, Caupi, Common Cowpea, Cow Pea, Cowpea, Frijol De Vaca, Frijol De Vara, Kulthi, Li-me, Lozy, Mahalaindolo, Me-karal, Mil-me, Pois Inconnu, Pois Liane, Pois Manger Cochon, Voahimba

M. Thulin. Flora of Somalia, Vol. 1–4 [updated 2008] https://plants.jstor.org/collection/FLOS

Morphology General Habit

Annual or perennial, erect to climbing herb; stems glabrous or slightly hairy

Morphology Leaves Leaflets

Leaflets 3, usually ovate or triangular, 1.5–16.5 x 1–12.5 cm, entire or 3-lobed, glabrous or sparsely pubescent on both surfaces

Morphology Leaves Stipules

Stipules submedifixed with an entire spur, 2–6 mm long

Morphology Reproductive morphology Inflorescences

Inflorescences subumbellate, few–several-flowered

Morphology Reproductive morphology Flowers Calyx

Calyx glabrous

Morphology Reproductive morphology Flowers Corolla

Standard white, greenish, yellow or purplish, 1.2–3.3 cm long, glabrous

Morphology Reproductive morphology Fruits

Pods 5.5–10 x 0.3–1.1 cm (may be longer in cultivated races), glabrous or scabrous

Morphology Reproductive morphology Seeds

Seeds ± oblong; hilum one-third to half the longest dimension, eccentric.

Use Animal Food

Used as animal food.

Use Environmental

Environmental uses.

Use Gene Sources

Used as gene sources.

Use Food

Used for food.

Use Materials

Used as material.

Use Medicines

Medical uses.

Use

Environmental, Food and Drink, Forage, Medicine, Weed