Which genus of fungi is responsible for the disease ergotism?

The genus Claviceps is responsible for ergotism. These fungi infect grasses and cereal crops, especially rye, and form dark, hardened structures called sclerotia in place of developing grains.

The best-known species is Claviceps purpurea, the rye ergot fungus. Its sclerotia contain ergot alkaloids, including compounds related to ergotamine and ergometrine. When contaminated grain is eaten, these substances can cause ergotism, a poisoning syndrome with either severe muscle spasms and neurological symptoms or intense blood-vessel constriction that may lead to tissue death.

Ergot has a long history in agriculture and medicine. Historical outbreaks were associated with contaminated rye, and the condition was once called Saint Anthony’s fire. Carefully controlled ergot-derived compounds later found medical uses, including drugs affecting uterine contractions and migraine treatment.

A common mistake is naming Claviceps purpurea when the question asks for the genus. C. purpurea is the principal species linked with classic rye ergotism, while Claviceps is the broader and correct genus-level answer.