The winged bean (''Psophocarpus tetragonolobus''), also known as , Goa bean, four-angled bean, four-cornered bean, manila bean, princess bean, star bean, kamrangi bean, pea, or dragon bean, is a tropical

herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of ...

legume Legumes are plants in the pea family Fabaceae (or Leguminosae), or the fruit or seeds of such plants. When used as a dry grain for human consumption, the seeds are also called pulses. Legumes are grown agriculturally, primarily for human consum ...

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

. Winged bean is widely recognised by consumers and farmers in

South Asia South Asia is the southern Subregion#Asia, subregion of Asia that is defined in both geographical and Ethnicity, ethnic-Culture, cultural terms. South Asia, with a population of 2.04 billion, contains a quarter (25%) of the world's populatio ...

and

South East Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

for its variety of uses and disease resistance. Winged bean is nutrient-rich and all parts of the plant are edible. The

leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...

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. Soy is a staple crop, the world's most grown legume, and an important animal feed. Soy is a key source o ...

. 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, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

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

herb Herbs are a widely distributed and widespread group of plants, excluding vegetables, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal purposes, or for fragrances. Culinary use typically distingu ...

aceous

perennial In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

, but can be grown as an annual. 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 bean, green, unripe pods. Its leaf is also occasionally used as a Leaf vegetable, vegetable and the straw as fodder. Its Pla ...

. 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 The genotype of an organism is its complete set of genetic material. Genotype can also be used to refer to the alleles or variants an individual carries in a particular gene or genetic location. The number of alleles an individual can have in a ...

. 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 colour 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 Fabaceae () or Leguminosae,International Code of Nomen ...

. Species in the ''Psophocarpus'' genus are perennial herbs grown as annuals. ''Psophocarpus'' species have tuberous roots and pods with wings. National Research Council (U.S.). (1975).
Underexploited Tropical Plants with Promising Economic Value
'. 2nd Edition. U.S. National Academies. 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''; , fossilized , also known as Papua or historically ) is the List of islands by area, world's second-largest island, with an area of . Located in Melanesia in the southwestern Pacific Ocean, the island is ...

, the species grows abundantly in the hot, humid equatorial countries of

South South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both west and east. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþa ...

and

Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

, as well as

tropical Africa The Afrotropical realm is one of the Earth's eight biogeographic realms. It includes Sub-Saharan Africa, the southern Arabian Peninsula, the island of Madagascar, and the islands of the western Indian Ocean. It was formerly known as the Ethiopi ...

. It is widely known in Southeast Asia and

Papua New Guinea Papua New Guinea, officially the Independent State of Papua New Guinea, is an island country in Oceania that comprises the eastern half of the island of New Guinea and offshore islands in Melanesia, a region of the southwestern Pacific Ocean n ...

, 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 Soil pH is a measure of the acidity or basicity (alkalinity) of a soil. Soil pH is a key characteristic that can be used to make informative analysis both qualitative and quantitatively regarding soil characteristics. pH is defined as the neg ...

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 In agriculture, cover crops are plants that are planted to ground cover, cover the soil rather than for the purpose of being harvested. Cover crops manage soil erosion, soil fertility, soil quality, water, weeds, Pest (organism), pests, diseases ...

; 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.

Composition

Nutrition

Uses

Culinary

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; it has 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 to it ...

and

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

, 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, vegetable greens, or simply greens, are plant leaves eaten as a vegetable, sometimes accompanied by their petioles and shoots, if tender. 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 vegetable Root vegetables are underground plant parts eaten by humans or animals as food. In agricultural and culinary terminology, the term applies to true roots, such as taproots and root tubers, as well as non-roots such as bulbs, corms, rhizomes, and ...

s. 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 breakdow ...

s and

hemagglutinin The term hemagglutinin (alternatively spelt ''haemagglutinin'', from the Greek , 'blood' + Latin , 'glue') refers to any protein that can cause red blood cells (erythrocytes) to clump together (" agglutinate") ''in vitro''. They do this by bindin ...

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 Mandalay is the second-largest city in Myanmar, after Yangon. It is located on the east bank of the Irrawaddy River, 631 km (392 mi) north of Yangon. In 2014, the city had a population of 1,225,553. Mandalay was founded in 1857 by Ki ...

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 Coconut milk is a plant milk extracted from the grated pulp of mature coconuts. The opacity and rich taste of the milky-white liquid are due to its high oil content, most of which is saturated fat. Coconut milk is a traditional food ingred ...

The beans are rich not only in protein, but in

tocopherol Tocopherols (; TCP) are a class of organic compounds comprising 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 rats, it was named ''t ...

s (antioxidants that facilitate vitamin-A utilisation in the body). They can be made into milk when blended with water and an

emulsifier An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Althou ...

. Winged bean milk is similar to

soy milk Soy milk (or soymilk), also known as soya milk, is a plant-based milk produced by soaking and grinding soybeans, boiling the mixture, and filtering out remaining particulates. It is a stable emulsion of oil, water, and protein. Its original ...

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

asparagus Asparagus (''Asparagus officinalis'') is a perennial flowering plant species in the genus ''Asparagus (genus), Asparagus'' native to Eurasia. Widely cultivated as a vegetable crop, its young shoots are used as a spring vegetable. Description ...

. 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. In Nagaland the fruit is eaten raw as salad and called ''charkona'' in the Nagamese creole. In the

Angami language Angami, also known as Tenyidie, is a Naga language spoken in the Naga Hills in the northeastern part of India, in Kohima district, Nagaland. In 2011, there is an estimate of 153,000 first language (L1) Angami speakers. Under the UNESCO's La ...

it is called kedia rücü.

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. They provide the balanced nutrition needed by farmed fish. The feeds, in the form of granules or pellets, give nutrition in a stable and concentrated form, enabling the ...

, 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, 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 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