One of the most poisonous plants in the UK, Deadly Nightshade is a member of the potato family (Solanaceae), along with tomatoes and aubergines. All parts of the plant are toxic, especially the berries, which contain a mixture of alkaloids which affect the nervous system. One of them, atropine, causes sweating, vomiting, breathing difficulties, confusion, hallucinations and death.
In very small quantities, though, atropine has medical applications. Atropine eye drops dilate the pupils, which is useful in opticians’ analyses. (Wide pupils were also considered attractive in the 15th and 16th centuries, and Nightshade drops were widely used for this reason – indeed, Linnaeus named the species belladonna, Italian for ‘beautiful lady’.) Injections of atropine are used to treat a very slow heart rate and other cardiac problems. Atropine also inhibits the production of saliva, and is sometimes used for this during surgery.