Ergot
Claviceps purpurea (Fr.) Tul.
Description
A parasite of rye and other grasses, replacing the grain with a dark spur-shaped body.
Curiosity
In the Middle Ages it caused outbreaks of St Anthony's fire.
Psychoactive compounds
alcaloides del cornezuelo
Risks
Its alkaloids cause ergotism: gangrene, convulsions and hallucinations, which can be fatal. Its legal status varies by country.