Jan. 12, 2023
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Physostigma venenosum, the Calabar bean or ordeal bean, is a leguminous plant that is endemic to tropical Africa, with a seed poisonous to humans. The Calabar bean contains physostigmine, an alkaloid that is a reversible cholinesterase inhibitor. The people of Old Calabar (also referred to as Callabar, Calabari, Calbari and Kalabar) in Nigeria used Calabar beans or '"E-ser-e" as an ordeal poison administered them to persons accused of witchcraft or other crimes: it was thought to affect only the guilty, so if a person accused of a crime ingested the beans without dying, they were considered innocent. Illustration from Franz Eugen Köhler's Medizinal-Pflanzen (Köhler HA. Köhler's Medizinal-Pflanzen in naturgetreuen Abbildungen mit kurz erläuterndem Texte: Atlas zur Pharmacopoea germanica, austriaca, belgica, danica, helvetica, hungarica, rossica, suecica, Neerlandica, British pharmacopoeia, zum Codex medicamentarius, sowie zur Pharmacopoeia of the United States of America. Band 2. Leipzig: von Ramm & Seemann, 1890).
(The chromolithograph is from Köhler's Medizinal-Pflanzen, a German herbal written principally by German physician and chemist Hermann Adolph Köhler (1834-1879) and originally published in two volumes: the first in 1887, the second in 1890. Illustration edited by Dr. Douglas J Lanska.)