The winged bean (''Psophocarpus tetragonolobus''), also known as , goa bean, four-angled bean, four-cornered bean, manila bean, princess bean, asparagus pea, dragon bean, is a tropical herbaceous legume

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclu ...

. Winged bean is widely recognised by farmers and consumers in

South Asia South Asia is the southern subregion of Asia, which is defined in both geographical Geography (from Greek: , ''geographia''. Combination of Greek words ‘Geo’ (The Earth) and ‘Graphien’ (to describe), literally "earth descr ...

for its variety of uses and

disease resistance Disease resistance is the ability to prevent or reduce the presence of diseases in otherwise susceptible hosts. It can arise from genetic or environmental factors, such as incomplete penetrance. Disease tolerance is different as it is the ability o ...

. Winged bean is nutrient-rich and all parts of the plant are edible. The leaves can be eaten like spinach, flowers can be used in salads, tubers can be eaten raw or cooked, and seeds can be used in similar ways as the

soybean The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean, which has numerous uses. Traditional unfermented food uses of soybeans include soy milk, from which tofu a ...

. The winged bean is an underutilised species but has the potential to become a major multi-use food crop in the

tropics The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referr ...

of Asia, Africa, and Latin America.

Description

The winged bean plant grows as a vine with climbing stems and leaves, in height. It is an herbaceous

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wid ...

, but can be grown as an

annual Annual may refer to: *Annual publication, periodical publications appearing regularly once per year ** Yearbook ** Literary annual *Annual plant *Annual report *Annual giving *Annual, Morocco, a settlement in northeastern Morocco *Annuals (band), ...

. It is generally taller and notably larger than the

common bean ''Phaseolus vulgaris'', the common bean, is a herbaceous annual plant grown worldwide for its edible dry seeds or green, unripe pods. Its leaf is also occasionally used as a vegetable and the straw as fodder. Its botanical classification, alo ...

. The leaves can be long. The shape of its leaves ranges from ovate to deltoid, ovate-lanceolate, lanceolate, and long lanceolate. The green tone of the leaves also varies. The stem is most commonly green, but sometimes boasts purple. The large flower is pale blue. The bean pod may be smooth or rough, depending on the genotype. It is typically long, rectangular in cross-section (though sometimes appearing flat), and has four wings with frilly edges running lengthwise. The skin is waxy and the flesh partially translucent in the young pods. The colour of the pods may be cream, green, pink, or purple. When fully ripe, the pod turns an ash-brown color and splits open to release the seeds (beans). The seed shape is often round; oval and rectangular seeds also occur. Seeds may appear white, cream, dark tan, or brown, depending on growing and storage conditions. The beans themselves are similar to

s in both use and nutritional content (being 29.8% to 39% protein).

Taxonomy

The winged bean belongs to the genus '' Psophocarpus'', which is part of the legume family, Fabaceae. Species in the ''Psophocarpus'' genus are perennial herbs grown as annuals. ''Psophocarpus'' species have tuberous roots and pods with wings.

National Research Council National Research Council may refer to: * National Research Council (Canada), sponsoring research and development * National Research Council (Italy), scientific and technological research, Rome * National Research Council (United States), part of ...

(U.S.). (1975).
Underexploited Tropical Plants with Promising Economic Value
'. 2nd Edition.

U.S. National Academies The National Academies of Sciences, Engineering, and Medicine (also known as NASEM or the National Academies) are the collective scientific national academy of the United States. The name is used interchangeably in two senses: (1) as an umbrell ...

. They can climb by twining their stems around a support.

Distribution and habitat

Most likely originating from

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torr ...

, the species grows abundantly in the hot, humid

equatorial Equatorial may refer to something related to: *Earth's equator **the tropics, the Earth's equatorial region **tropical climate *the Celestial equator ** equatorial orbit **equatorial coordinate system ** equatorial mount, of telescopes * equatorial ...

countries of South and

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainlan ...

, as well as

tropical Africa Although tropical Africa is mostly familiar to the West for its rainforests, this biogeographic realm of Africa is far more diverse. While the tropics are thought of as regions with hot moist climates, which are caused by latitude and the trop ...

. It is widely known in Southeast Asia and

Papua New Guinea Papua New Guinea (abbreviated PNG; , ; tpi, Papua Niugini; ho, Papua Niu Gini), officially the Independent State of Papua New Guinea ( tpi, Independen Stet bilong Papua Niugini; ho, Independen Stet bilong Papua Niu Gini), is a country i ...

, but only cultivated on a small scale. It tends to be found in open areas and old garden sites, less so in the forest.

Ecology

Germination

Winged bean is a self-pollinating plant but mutations and occasional outcrossing, may produce variations in the species. The pretreatment of winged bean seeds is not required in tropical climate, but scarification of seeds has shown to enhance the germination rate of seedlings. Seed soaking may also increase speed to germination, as is typical, and may be used in conjunction with scarification. Seedlings under natural field conditions have been reported to emerge between five and seven days. Winged bean can grow at least as fast as comparable legumes, including soy. Plants flower 40 to 140 days after sowing. Pods reach full-length about two weeks after pollination. Three weeks after pollination, the pod becomes fibrous; after six weeks, mature seeds are ready for harvest. Tuber development and flower production vary according to genotype and environmental factors. Some winged bean varieties do not produce tuberous roots. The winged bean is a tropical plant, and will only flower when the day length is shorter than 12 hours, although some varieties have been reported to be day-length neutral. All varieties of winged bean grow on a vine and must grow over a support. Some examples of support systems include: growing against exterior walls of houses, huts, buildings; supporting against larger perennial trees; stakes placed in the ground vertically; and structures made from posts and wires. Because the early growth of winged bean is slow, it is important to maintain weeds. Slow early growth makes winged bean susceptible to weed competition in the first four to six weeks of development. Khan (1982) recommends weeding by hand or animal drawn tractor two times before the support system of the winged bean is established. Winged bean can be grown without added fertiliser as the plant has a bacterium on the nodules of the roots that fixes nitrogen and allows the plant to absorb nitrogen. Factors that influence nitrogen fixation include, Rhizobium strain, interactions between strain and host genotype, available nutrients and soil pH.

Growing conditions

Although winged bean thrives in hot weather and favours humidity, it is adaptable. The plant's ability to grow in heavy rainfall makes it a candidate for the people of the African tropics. Winged bean production is optimal in humidity, but the species is susceptible to

moisture stress Moisture stress is a form of abiotic stress that occurs when the moisture of plant tissues is reduced to suboptimal levels. Water stress occurs in response to atmospheric and soil water availability when the transpiration rate exceeds the rate of w ...

and waterlogging. Ideal growing temperature is 25 °C. Lower temperatures suppress germination, and extremely high temperatures inhibit yield. Even moderate variations in the growing climate can affect yield. Growing winged bean in lower temperatures can increase tuber production. Leaf expansion rate is higher in a warmer climate. For the highest yields, the soil should remain moist throughout the plant's life cycle. Although the plant is tropical, it can flourish in a dry climate if irrigated. If the plant matures during the drier part of the growing season, yields are higher. Winged bean is an effective cover crop; planting it uniform with the ground suppresses weed growth. As a restorative crop, winged bean can improve nutrient-poor soil with nitrogen when it is turned over into the soil.

Uses

The entire winged bean plant is edible. The leaves, flowers, roots, and bean pods can be eaten raw or cooked; the pods are edible even when raw and unripe. The seeds are edible after cooking. Each of these parts contains vitamin A, vitamin C,

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...

and

iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...

, among other nutrients. The tender pods, which are the most widely eaten part of the plant, are best when eaten before they exceed in length. They are ready for harvest within three months of planting. The flowers are used to colour rice and pastry. The young leaves can be picked and prepared as a

leaf vegetable Leaf vegetables, also called leafy greens, pot herbs, vegetable greens, or simply greens, are plant leaves eaten as a vegetable, sometimes accompanied by tender petioles and shoots. Leaf vegetables eaten raw in a salad can be called salad gre ...

, similar to spinach. The nutrient-rich, tuberous roots have a nutty flavour. They are about 20% protein; winged bean roots have more protein than many other root vegetables. The leaves and flowers are also high in protein (10–15%). The seeds are about 35% protein and 18% fat. They require cooking for two to three hours to destroy the

trypsin inhibitor A trypsin inhibitor (TI) is a protein and a type of serine protease inhibitor (serpin) that reduces the biological activity of trypsin by controlling the activation and catalytic reactions of proteins. Trypsin is an enzyme involved in the breakdown ...

s and

hemagglutinin In molecular biology, hemagglutinins (or ''haemagglutinin'' in British English) (from the Greek , 'blood' + Latin , 'glue') are receptor-binding membrane fusion glycoproteins produced by viruses in the '' Paramyxoviridae'' family. Hemagglutinins a ...

s that inhibit digestion.National Research Council. The winged bean : a high-protein crop for the tropics : report of an ad hoc panel of the Advisory Committee on Technology Innovation. Board on Science and Technology for International Development, 1981 They can be eaten dried or roasted. Dried and ground seeds make a useful flour, and can be brewed to make a coffee-like drink. Image:Japanese_Psophocarpus_tetragonolobus.jpg, Winged bean pods Image:Wingedbean_roots.JPG, A young Burmese woman sells winged bean roots at a market in Mandalay File:Pè myit.jpg, Boiled winged bean roots served as a snack in Burma File:Sigarilyasjf1338.JPG, '' Ginataang sigarilyas'', a Filipino dish of winged bean (''sigarilyas'') in coconut milk The beans are rich not only in protein, but in

tocopherol Tocopherols (; TCP) are a class of organic chemical compounds (more precisely, various methylated phenols), many of which have vitamin E activity. Because the vitamin activity was first identified in 1936 from a dietary fertility factor in rat ...

s (antioxidants that facilitate vitamin-A utilisation in the body).

(U.S.), 1975 They can be made into milk when blended with water and an emulsifier. Winged bean milk is similar to

soy milk Soy milk (simplified Chinese: 豆浆; traditional Chinese: 豆漿) also known as soya milk or soymilk, is a plant-based drink produced by soaking and grinding soybeans, boiling the mixture, and filtering out remaining particulates. It is a sta ...

, but without the bean-rich flavour. The flavour of raw beans is not unlike that of

asparagus Asparagus, or garden asparagus, folk name sparrow grass, scientific name ''Asparagus officinalis'', is a perennial flowering plant species in the genus '' Asparagus''. Its young shoots are used as a spring vegetable. It was once classified in ...

. Smoked pods, dried seeds, tubers (cooked and uncooked), and leaves have been sold in domestic markets in South East and South Asia. Mature seeds can command a high price.

As animal feed

Winged bean is a potential food source for ruminants, poultry, fish, and other livestock. For

commercial fish feed Manufactured feeds are an important part of modern commercial aquaculture, providing the balanced nutrition needed by farmed fish. The feeds, in the form of granules or pellets, provide the nutrition in a stable and concentrated form, enabling t ...

, winged bean is a potentially lower-cost protein source. In Africa, fish meal is especially scarce and expensive.Fagbenro, A. (1999). Comparative evaluation of heat-processed Winged bean Psophocarpus tetragonolobus meals as partial replacement for fish meal in diets for the African catfish Clarias gariepinus. Aquaculture 170 (1999), 297-305. The

African sharptooth catfish ''Clarias gariepinus'' or African sharptooth catfish is a species of catfish of the family Clariidae, the airbreathing catfishes. Distribution They are found throughout Africa and the Middle East, and live in freshwater lakes, rivers, and sw ...

, a highly valued food fish in Africa, can eat winged bean. In Papua New Guinea highlands region where winged beans thrive, the husks are fed to the domesticated pigs as a dietary supplement.

Notes

Sources

*National Research Council. The winged bean : a high-protein crop for the tropics : report of an ad hoc panel of the Advisory Committee on Technology Innovation. Board on Science and Technology for International Development, 1981