In Sherlock Holmes’s story “The Adventure of the Devil’s Foot,” the poisonous root is found in Africa.
The case takes place in Cornwall, where Holmes is recovering from overwork with Dr Watson. They meet Mr Sterndale, an explorer who knows about a rare African substance called the devil’s-foot root. The root is associated with a dangerous poison that can cause terrifying effects when burned.
Holmes tests the substance despite Watson’s objections, briefly exposing himself to its fumes. The experiment demonstrates how seriously Holmes’s curiosity can endanger him, even when he is investigating a crime rather than confronting a criminal directly.
The story combines detective fiction with an exotic poison and an exploration narrative. The root is fictionalized in Doyle’s account, so it should not be confused with a standard medical identification of an actual African plant.