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Winged bean, Four angled bean [Psophocarpus tetragonolobus (L.) DC.]


The situation in Japan and information from the NIAS genebank
Winged bean is called "Sikaku mame (four angled bean)" in Japan. This crop has not been cultivated in Japan. Recently (in 1986), a variety named "Urizun"was released from the Ministry of Agriculture, Forestry and Fisheries (MAFF) Japan. This variety is grown for young green pods during summer time mainly in Okinawa prefecture (the southernmost islands in Japan).
There are two hypothesises for the region of domestication. One is in Africa on the basis of "linguistic" evidence (Burkill,1935 referred in Smartt, 1980) and another is in tropical Asia (Smartt, 1980).
According to Smartt (1980), a wild species (probably P.grandiflorus) was transferred to tropical Asia from Africa and was domesticated in tropical Asia (transdomestication theory).
In the genus Psophocarpus, 8 wild species are known to be distributed in Africa, while one crop species (winged bean) is mainly cultivated in tropical Asia and New Guinea. 2n=18 (20).
Winged bean is a perennial food legume cultivated mainly on humid highland of tropical Asia and New Guinea.
Flower color is bluish purple. Pod length is from 15 to 30cm. Cross section of the pod is tetragonal shape with wing on each angle. Seed is round. Color of the seed ranges from black, brown, yellow, white to various types of mottled color.
Cultivation for tuber production is widely seen on the highland of New Guinea and Myanmar (Shan States).
Young pods and flowers are used as vegetables. Root tubers are also used as fresh or cooked in the same manner as potato.
Burkill,I.H. 1935. A Dictionary of the Economic Products of the Malay Peninsula. London: Crown Agents.
Smartt,J. 1990. Grain Legumes : Evolution and Genetic Resources. Cambridge University Press. p.266.