Psophocarpus tetragonolobus

A perennial herbaceous plant growing to 2m tall, hardy to UK zone 10 and frost tender. Hermaphrodite flowers pollinated by insects. Nitrogen-fixing legume. Grows in sandy, loamy, and clay soils with good drainage, tolerating heavy clay. Adapts to mildly acid, neutral, and basic soils. Requires full sun and moist soil.

Description

A climbing perennial bean up to 3 or 4 m tall. It can re-grow each year from the fattened roots. The stems twine around supports or trail over the ground. The leaves have 3 leaflets. The leaf stalks are long. The leaflets are 8-15 cm long. The flowers are blue or white. They occur on the ends of branches from within the axils of leaves. Pods have wavy wings or are roughly square in cross section. They are 6-36 cm long with 5-30 seeds. Seeds can be white, yellow, brown or black. They are bedded in the solid tissues of the pod. The seeds are round smooth and brown with a small hilum. Nodules on the roots are many and large.

Edible Uses

Young seedpods are cooked for a few minutes and taste similar to French beans. Pods are harvested when about 15–20cm long and 2cm wide, and will store for up to 21 days at 10°C with 90% relative humidity. Average pod yields are 250–500g per m². Immature seeds can be used in soups and similar dishes. Mature seeds are eaten cooked; they are very nutritious, containing up to 17% oil, and are also rich in protein, vitamin E, and calcium. Seeds can be roasted and eaten like peanuts or fermented and used as tempeh. An edible oil is extracted from the seed. The root can be eaten raw or cooked like potatoes; it is slightly sweet and contains 20% or more protein, approximately 12 times that of potatoes. Leaves and young shoots are cooked and used like spinach. Flowers and flower buds can be eaten raw or cooked, with a flavour similar to mushrooms when sautéed. The light blue flowers are also used as a food colouring. Roasted seeds serve as a coffee substitute.

Traditional Uses

The young pods are edible. The ripe seeds are edible. The young leaves are edible. The flowers are edible. The root tubers are edible. The seeds can be used to extract an edible oil.

Medicinal Uses

None known.

Distribution

A tropical plant. The bean grows from sea level up to about 1850 m altitude in the tropics. It normally only produces tubers between 1200 and 1850 m. Because of the effect of daylength it will not produce flowers or pods at places far removed from the equator. Photoperiodism limits pod availability in higher latitudes but this should not be significant in the equatorial latitudes. Winged bean is a short day plant. It needs a daylength less than 12 hours. Winged bean is a plant ideally suited to the tropics including the hot humid lowlands. Papua New Guinea is a centre of diversity for winged beans and they are grown in many areas of the country. They can be seen from sea level up to about 2300 m altitude although they are less common above 1850 metres and normally only produce tubers between 1200 and 1850 m altitude. For maximum seed production winged beans need temperatures between 23°C and 27°C and for tubers the temperatures should be between 18°C and 22°C. This means the main areas of production occur between 20°N and 10°S latitudes. Winged beans can grow on a wide variety of soils. Winged beans have been grown on soils with pH from 3.6 to 8.0. Soils which are very acid have soluble aluminium to which winged beans are sensitive. Soils should not be waterlogged. In Yunnan.

Where It Grows

Africa, Asia, Bangladesh, Bougainville, Brazil, Cambodia, Cameroon, Caribbean, Central Africa, China, Congo, Cook Islands, Côte d'Ivoire, Cuba, East Africa, East Timor, Egypt, Fiji, French Polynesia, FSM, Ghana, Guam, Hawaii, India, Indochina, Indonesia, Ivory Coast, Japan, Laos, Libya, Madagascar, Malaysia, Marianas, Mauritius, Myanmar, Nigeria, North Africa, Northeastern India, Pacific, Papua New Guinea*, PNG, Philippines, Pohnpei, Puerto Rico, Reunion, SE Asia, Senegal, Sierra Leone, Singapore, Solomon Islands, South America, Sri Lanka, Tahiti, Taiwan, Tanzania, Thailand, Timor-Leste, USA, Vanuatu, Vietnam, West Africa, West Indies, Zambia,

Cultivation

Seeds are sown at the beginning of the rainy season. Seeds germinate and grow slowly for the first 3 or 5 weeks. For tubers, vines are pruned off at about 1 m high (or left unstaked) and some flowers are removed. Winged beans are grown for their edible roots, edible leaves, edible flowers, edible pods and edible seeds. The cultivation procedures vary slightly depending on which product is the preferred goal. The two main types of winged bean are short podded ones which are used for tubers and long podded ones which have poor tubers. Tuber production is not as efficient in tropical lowland conditions. Production is from seed. Phases of development:- 1. Germination 5-16 days; 2. Vegetative growth till flower buds 46-92 days; 3. Flowering duration ? 4. Pod development 10-13 weeks after planting; 5. Tuber development 4-5 months after planting. Winged beans are predominantly self pollinated but limited out-crossing has been reported. Hard seed coats have been reported from dried stored seed. The amount of vegetative growth increased with increasing pH from 4.7 to 5.5. Nitrogen percentage in tissues increased with pH from 4.7 to 6.2 Winged beans have been grown in soils with pH between 3.6 and 8.0. Winged bean is sensitive to aluminium in soil solution. Plants are intolerant of water-logging. Flowering is inhibited by low levels of solar radiation. Shading improves pod length and seed number. Root knot nematode can cause severe damage in some places. Seeds are planted 2-3 cm deep and about 25-35 cm apart. If seeds have been dried and stored then they can suffer from hard seed coats and this delays the germination of seeds. But normally seeds start to grow in about 15 or 16 days. Plants grow slowly to start with so weeding is important but then they grow rapidly. After 46 to 92 days they are producing flowers. If fattened roots are important some of the leaves and flowers and tips are pruned off at this stage. These can be eaten. Pods develop 10 to 13 weeks after planting and tubers occur 4-5 months after planting. For tubers production plants are planted seasonally to allow them to mature during the dry season. Winged beans need to be staked for high yields. Winged bean root nodules containing Rhizobia bacteria are very large, inoculation occurs easily and naturally and nitrogen fixation is efficient. This both enables winged beans to grow well and have a high protein content but can also help provide nitrogen in the soil for other plants.

Propagation

Pre-soak seed for 12 hours in warm water, then sow in early spring in a warm greenhouse. Place two or three seeds per pot and thin to the strongest plant. Plant out in late spring or early summer after the last expected frosts, providing cloche or cold frame protection until plants are growing away strongly.

Other Uses

An excellent green manure with exceptional nitrogen-fixing properties, producing a greater weight of root nodules per plant than any other member of the Leguminosae family. Used for soil improvement and restoration.

Production

The first green pods are ready about 10 weeks after sowing. Tubers are ready after 4-8 months. Seed yields of 1.2 tons/ha and tuber yields of 4 tons/ha are possible. A single plant can produce up to 75 pods. Dry bean yields of 45 to 330 g per plant can be produced depending on variety. Tuber yields of 5500 to 12000 kg per hectare have been produced. Seeds can contain a trypsin inhibitor which reduces protein digestibility. This inhibitor is destroyed by soaking seeds then boiling them well. Tubers can also contain this chemical and need to be well cooked.

Other Information

It is a commercially cultivated vegetable. Very important for tubers in the Eastern and Western Highlands of Papua New Guinea and moderately common for beans in other places.

Notes

Demo. Seeds are rich in tocopherol - Vitamin A (126 mg/100 g fresh weight)

Nutrition

Synonyms

Also Known As

Almongo, Betlanei, Calasmismis, Charfakia, Chipir, Dambala, Dara-dhambala, Dau-rong, Dugaro, Far, Fava de cavalo, Fogiolo quadrato, Four angled bean, Goa bean, Goabohne, Kacang belimbing, Kacang botor, Kacang jorbing, Kachang belimbing, Kachang botol, Kachang botor, Kalo, Kechipir, Kecipir, Manilla bean, Paramka, Paro, Parpila, Pesai, Pois asperge, Prapiey chrung, Puti, Sai are, Samporong, Sbai daograng, Sem, Shamtorkari, Shikakumame, Si jiang dou, Sigarilyas, Sikaku mame, Su-ling dou, Sz kok tau, Tengnoumanb, Thua phuu, Thua pu, Tua pu, Wenali-wenali

References (72)

• Abberton, M., et al, 2020, Winged bean, Psophocarpus tetragonolobus. Legume Perspectives. Issue 19. November 2020
• Abbiw, D.K., 1990, Useful Plants of Ghana. West African uses of wild and cultivated plants. Intermediate Technology Publications and the Royal Botanic Gardens, Kew. p 31
• Ambasta S.P. (Ed.), 2000, The Useful Plants of India. CSIR India. p 499
• Anderson, E. F., 1993, Plants and people of the Golden Triangle. Dioscorides Press. p 219
• Arora, R. K., 2014, Diversity in Underutilized Plant Species - An Asia-Pacific Perspective. Bioversity International. p 50

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