Canavalia gladiata

Canavalia gladiata, the sword bean or scimitar bean, is a domesticated plant species in the legume family Fabaceae. It is used as a vegetable in interior central and south central India, though not commercially farmed. The unripe pods are also eaten as a vegetable in Africa and Asia. The term "sword bean" is also used for other legumes, notably the common jack bean Canavalia ensiformis.

Description

A climbing or sometimes bushy and upright bean plant. Mostly it is a climber. It can be 4 m long. The leaves have 3 large leaflets. The leaflets are oval and 7.5-20 cm long by 5-12 cm wide. The top of the leaf can narrow abruptly to a tip while the base can be rounded or broadly wedge shaped. The leaves are slightly hairy on both surfaces. The leaf stalk is 5-12 cm long. The flowers are in groups and are white. The flower cluster is 7-12 cm long and the flower cluster stalk 4-20 cm long. The individual flower stalks are 2 mm long. The pods are long (20-40 cm) and curved. Seeds are coloured red or pink. The hilum is dark brown and almost as long as the seed.

Edible Uses

Young seedpods can be eaten raw but are more commonly cooked as a vegetable. Each pod is 20–30cm long and 2cm wide. The seeds must be thoroughly boiled to destroy a toxic alkaloid; the seedcoats are often removed first, and the seeds are then cooked in two or three changes of water. Large pods, 30–45cm long, are produced toward the end of summer, and the seeds swell gradually over several weeks — they fatten much more slowly than peas. It takes practice to judge when they are fully matured, otherwise little food is obtained from each pod. They make a useful haricot bean alternative.

Traditional Uses

Young pods are cooked and eaten. Seeds can be cooked and eaten, but the water should be changed and they should be well boiled. They are also fermented. The seeds can be toasted and ground and used as a coffee substitute. The leaves are blanched and eaten. CAUTION The seeds can be poisonous due to hydrocyanic acid and saponin. Cooking will remove these.

Medicinal Uses

Urease is extracted from the seed for use in clinical laboratories for the in-vitro determination of urea in human blood. In Korea, the plant is used to treat vomiting, abdominal dropsy, kidney-related lumbago, asthma, obesity, stomach-ache, dysentery, coughs, headache, intercostal neuralgia, epilepsy, schizophrenia, inflammatory diseases, and swellings. A soap based on sword bean extracts is marketed there for treating athlete's foot and acne. In Japan, the plant is used to treat ozena, haemorrhoids, pyorrhoea, otitis media, boils, cancers, all kinds of inflammatory diseases, and atopic dermatitis.

Known Hazards

Despite nutritional potential in terms of protein content sword beans are not used as food. This is partly due to the presence of harmful factors such as haemagglutinis (concanavalin A), protease inhibitors, hydrocyanic acid, tannins, phytates and canavanine. Canavanine is contained in the seeds of the plants (the content is 10–13%). It interferes with protein synthesis and has a nutrition-inhibiting effect on animals and humans. Soaking overnight and boiling in excess water followed by decanting resulted in the greatest reduction in canavanine content (approx. 50%), followed by boiling and decanting in excess water (34%).

Distribution

A tropical plant. It requires a tropical climate. Temperatures of 20-30°C suit it well and it grows from sea level to about 1000 m altitude in equatorial zones. They are drought and salt resistant. They can grow on lowland tropical nutrient depleted soils. They can grow on soils with pH from 4.5-7.0. They can tolerate some shade. In Yunnan.

Where It Grows

Africa, Angola, Argentina, Asia, Australia, Bangladesh, Benin, Brazil, Burundi, Cambodia, Central Africa, Central America, China, Congo DR, Cuba, East Africa, Fiji, Ghana, Guadeloupe, Guatemala, Guianas, Haiti, Hawaii, Honduras, India, Indochina, Indonesia, Jamaica, Japan, Korea, Laos, Madagascar, Malaysia, Mauritius, Mexico, Mozambique, Myanmar, Nigeria, North America, Northeastern India, Pacific, Panama, Papua New Guinea, PNG, Paraguay, Philippines, SE Asia, Seychelles, Singapore, Solomon Islands, South Africa, Southern Africa, South America, Sri Lanka, Suriname, Taiwan, Tanzania, Thailand, USA, Vietnam, West Africa, West Indies, Zambia, Zimbabwe,

Cultivation

They are grown from seeds. Seeds germinate readily and the plant is relatively fast growing. Seeds can be sown 5 cm deep. Plants should be 60-70 cm apart. Climbing types need support. Often natural supports such as trees, walls and fences are used in backyard production. For large scale production 25-40 kg/ha of seed are needed.

Propagation

Sow seed in situ, placing seeds 2–3cm deep in the soil. Germination occurs in approximately 72 hours.

Other Uses

The plant is sometimes grown as a green manure crop or temporary ground cover, and is also used as an ornamental climber on fences and houses, though it is short-lived. It is believed to repel snakes. The seed is used as feed for cattle and chickens, but dry seeds consumed in considerable quantity may cause poisoning.

Production

Green seeds/pods are produced in 3-4 months and mature seeds in 5-10 months. Seed yields of 700-900 kg/ha are possible. Green pods are hand picked when 10-15 cm long before they swell and become fibrous.

Other Information

It is a commercially cultivated vegetable. Pods are sold in local markets. Only occasionally grown in Papua New Guinea.

Notes

There are about 50 Canavalia species.

Nutrition

Synonyms

Also Known As

Abai, Abbo, Alad, Baikang, Baikng, Bara sem, Bo ba ji noe, Bon shim, Carabanz, Chemma kaaya, Dau-rua, Frijol cafe, Frijol de machete, Ghevada, Habas, Jangli Sem, Jungli abhui, Kacang parasman, Kacang polong, Kachang hantu, Kachang nyonya, Kachang parang, Kaos parasman, Kara pedang, Kara wedung, Koas bakol, Lal kadsumbal, Madezo, Magtambokau, Makhan shim, Moushim, Naga sem, Nam-nawbaw, Namtaipee, Nkasa, Pe-dalet, Pe-dama, Pe-damouk, Pe-det, Pe-gale, Pe-naung-ni, Rar bu-shot kwen-e, Sanndaek triehs, Scimitar-bean, Segapu thambattai, Sem, Shembi avare, Tarvardi, Thampattai, Thua phraa, Tioeuhs, Tua pra, Tumbekai, Yerra tamma

References (67)

• Sword bean references Canavalia gladiata
• Ambasta S.P. (Ed.), 2000, The Useful Plants of India. CSIR India. p 101
• Arinathan, V., et al, 2007, Wild edibles used by Palliyars of the western Ghats, Tamil Nadu. Indian Journal of Traditional Knowledge. 6(1) pp 163-168
• BARC, 2016, State of Biodiversity for Food and Agriculture in Bangladesh. Bangladesh Agricultural Research Council.
• Bircher, A. G. & Bircher, W. H., 2000, Encyclopedia of Fruit Trees and Edible Flowering Plants in Egypt and the Subtropics. AUC Press. p 80

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