Physostigma venenosum, the Calabar bean or ordeal bean, is a leguminous plant, Endemic to tropical Africa, with a seed poisonous to humans. It derives the first part of its scientific name from a curious beak-like appendage at the end of the stigma, in the centre of the flower; this appendage, though solid, was supposed to be hollow.

Sir Thomas Richard Fraser was a British physician and pharmacologist. Together with Alexander Crum Brown he discovered the relationship between physiological activity and chemical constitution of the body.