The Calabar bean, widely called as ordeal bean or chop nut, is a dark brown, kidney shaped seed, much like any ordinary seed, of a leguminous plant, Physostigma venenosum. The plant is a perennial woody structure with its creepers climbing high on tall trees, extending more than fifty feet in the air. An inhabitant of tropical Africa, the plant seeds are toxic to humans and prove fatal most of the times. The plant got the first part of its scientific name from its beak like attachment at the bottom edge of the stigma, in the middle of the flower. This attachment, though hard was believed to be hollow.
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Description of the calabar plant
Physostigma venenosum is a large herbaceous plant with the stem, 2 inches wide, woody at the base. The plant bears sizeable, may be as big as an inch, purple colored flowers, grouped in pendulous, gaudy and beautifully veined. The seed shells grow up to 6 inches in length and each encloses 2 to 3 dark chocolaty seeds, much similar to a usual horse bean though their shells are extremely tough and thicker. The plant was first sighted in the year 1846 and planted in the Edinburg Botanical Gardens. Though the Calabar beans ripe at all seasons, rainy days in Africa, from June to September, are associated with better quality seeds in larger quantities.
As the name suggests, the plant is indigenous to a part of Africa around Nigeria once commonly known as Calabar. It was an accustom there to use seeds as an “ordeal poison” to ascertain if the accused is a witch or was under the influence of evil spirits. The highly poisoned bean of Calabar, locally termed as “esere” was given to the blamed to eat. It was believed that if the seed was rejected by the stomach of the accused and he survived the ordeal, his innocence was then proclaimed. Hence, a Calabar bean could be rightly termed as Lie Detector Bean.
Western settlers detained by the native tribes and underwent the “ordeal”, soon discovered that by ingesting the bean in one gulp, they could prohibit the release of toxic constituents from inside and hence could survive the torment. A draught of the crushed seeds infused in water can prove fatal to a man within an hour. Although highly toxic, these beans don’t have any characteristic smell, taste or any other external aspect that could help distinguish them from harmless leguminous seeds which can turn out to be disastrous if left unattended in the way of kids.
Medicinal Uses of Calabar bean
The plant has been known to contain alkaloid physostigimine which help prolong the neuronal activity of acetylcholine. Calabar beans are clinically used for eye diseases, causes rapid contraction of eye pupil resulting in disturbed vision. This makes the plant a chief constituent of eye drops. In addition, these seeds act as a stimulant to the muscles of the intestines giving relief in chronic constipation. Calabar seeds are used internally for their depressant action in cholera, epilepsy, as they depress the nervous system causing slow pulse rate, high blood pressure and weakening of muscles. The uses of Calabar plant are limited because of its toxic nature.