Physostigma venenosum

The above illustration of the calabar bean, Physostigma venenosum , is taken from the relatively rare 1887 book, Köhler’s Medicinal Plants . Native to west Africa , the calabar bean is highly toxic to humans, and was allegedly used to determine guilt in witchcraft trials. Subjects of the trials would consume this “ordeal bean,” whose toxicity would overpower all but the innocent.

The company Franz Eugen Köhler published its four-volume medicinal guide in 1887 in Gera , a German town south of Leipzig . Containing nearly 300 chromolithographic images, the work was edited by the botanist Gustav Pabst.