Bean, Kidney

(Phaseolus vulparis L., Papilionaceae)

Also Called: Haricot.

Description: Some 500 varieties of this species are cultivated either as climb­ing plants or as dwarf forms. Leaves generally of 3 oval leaflets with acute apices, the upper surface being rough and hairy. Flowers, 1-2cm (0-4-0-8 in), white, lilac or pink. According to the variety the fruits are 10-30cm (4-12in) long, the fruit walls are fleshy or thin, green or yellowish. Since the medicinal activity is in the fruit wall, the fleshy varieties are preferred to those with large seeds. It is not yet known whether the green and spotted varieties are better as a medicament than the yel­low varieties. Taste of dried pods: insipid.

Part Used: Dried pods freed from seeds; also the fresh entire beans.

Habitat: Native of tropical America; cultivated throughout Europe. The pods should be dried in the shade.

Constituents and Action: Substances named glucoquinines and abundant silicic acid. The pods are diuretic and they slightly lower the blood sugar level in diabetics(action uncertain). Raw beans contain a toxic albumin which is destroyed on cooking.

Usage: principally as a decoction (soak for several hours 3-4 handfuls of finely chopped pods in 2 litres (3pts) of water, boil rapidly and allow to stand) for dropsy and diabetes. In the latter case, the decoction has only a supporting action and does not cure diabetes.