Phaseolus coccineus L.

[Scarlet runner bean]

To Japanese version

<The situation in Japan and information from the NIAS genebank>

The scarlet runner bean is cultivated in the north and northeastern part of Japan (Tohoku district, Hokkaido) and also in the cool highlands in central Japan. Red-flowered and white-flowered cultivars are usually planted together. This legume is believed to have been introduced in the late Edo period (19th century) by the Dutch (Hoshikawa, 1981). At first, it was used as an ornamental plant. It is called "benibana ingen" (scarlet-flowered common bean) or "hana mame" (flower bean). In Japan, dry seeds are cooked as "nimame" (boiled bean sweetened with sugar) and "ama-nattoh" (bean boiled with molasses and sprinkled with sugar). Young pods are also used as vegetables.

<Origin>

The scarlet runner bean is believed to have been domesticated in Central America, possibly in Mexico. Remains of domesticated P.coccineus dated more than 2000 years B.P. have been found in Tehuacan (Mexico), and wild P.coccineus from Ocampo (Mexico) have been dated as over 7000 years old (Kaplan,1965, cited from Smartt, 1990).

<Taxonomy>

The genus Phaseolus, together with the closely related genus Vigna, forms a very complicated taxonomic group, the so-called Phaseolus-Vigna complex. Verdcourt (1970) proposed a very restricted concept for Phaseolus, limiting it exclusively to those American species with a tightly coiled style and pollen grains lacking coarse reticulation, hence, promoting significantly the concept of Vigna. Marechal et al. (1978) followed Verdcourt and presented a monograph on the Phaseolus-Vigna complex. Their taxonomic system is now generally accepted. There are some 30 species described in the genus Phaseolus according to their monograph. They recognized four subspecies in Phaseolus coccineus, i.e., subsp.coccineus, subsp.obvallatus, subsp.formosus and subsp.polyanthus. 2n=22.

<Morphological characteristics>

the scarlet runner bean is a perennial plant of the humid tropical uplands. It is killed by frost and therefore is grown as an annual crop in temperate countries. It usually grows in twinning form to 4m or more in height. Flower color is either bright scarlet or white. Seed color is either dark purple mottled with black (bright scarlet-flowered variety) or white (white-flowered variety). Seed size is 1.8-2.5 x 1.2-1.6cm. Germination is hypogeal.

<Uses>

In temperate countries, it is usually grown for its tender pods which are sliced and cooked (Purseglove,1974). In Central America, the green and dry seeds are eaten. It is occasionally grown as an ornamental. The fresh tubers are boiled and eaten in Central America.

<References>

Hoshikawa,K. 1981. Benibana Ingen (Scarlet runner bean). In "Shokuyou Sakumotsu" (Food Crops). Yoken-do, Tokyo. (in Japanese) pp.495-497.

Marechal,R., J.M.Mascherpa and F.Stainer. 1978. Etude taxonomique d'un groupe complexe d'speces des genres Phaseolus et Vigna (Papilionaceae) sur la base de donnees morphologiques et polliniques, traitees par l'analyse informatique. Boissiera 28 : 1-273.

Purseglove, J.W. 1974. Phaseolus coccineus In "Tropical Crops : Dicotyledons." London : Longman. pp.295-296.

Smartt,J. 1990. Grain Legumes. Cambridge University Press. pp.85-139.

Verdcourt,B. 1970. Studies in the Leguminosae - Papilionoideae for the Flora of Tropical East Africa : IV. Kew Bulletin 24.