New records solve the mystery of Sherlock Holmes’s expertise in poisonous plants

Sir Arthur Conan Doyle, creator of the great detective, took a break from his medical studies to attend a course in botany at Edinburgh's Royal Botanic Garden


“Knowledge of Botany: Variable. Well up in belladonna, opium, and poisons generally. Knows nothing of practical gardening.”


That was Dr Watson’s assessment of his friend Sherlock Holmes’s expertise in plant sciences, as revealed in Sir Arthur Conan Doyle’s first outing for the detective, A Study in Scarlet.

And now we know where Holmes got his knowledge – from the man who created him.

Newly unveiled records dating back to 1877 show that Doyle interrupted his training as a medical doctor to take a course at the Royal Botanic Garden in Edinburgh. Doyle attended around 60 classes, as well as demonstrations and field excursions, and his signature can be seen on the register from the course.

He put his knowledge to good use in his Sherlock Holmes short stories, with a number of tales featuring deadly poisons, most notably The Adventure of the Devil’s Foot which sees an entire family driven mad after they inhale the vapour from a burning root, Latin name radix pedis diabolic, obtained by the killer during his travels in Africa.

Holmes was of course well versed in the use of other plant-based poisons too – namely opium and cocaine – if only for recreational purposes…

Read more about the discovery in this blog by Leoni Paterson, archivist at the Royal Botanical Garden Edinburgh