What is the X in X-mas?
fungal disease of rye and other grasses, 1680s, from French ergot, from Old French argot "cock's spur" (12c.), of unknown origin. The blight so called from the shape the fungus forms on the diseased grain. Ergotism "disease caused by eating ergot-infected breadstuffs," first recorded 1853. An alkaloid from the fungus, ergotamine (1921) is used to treat migraines.
ergot er·got (ûr'gət, -gŏt')
A fungus that infects various cereal plants and forms compact black masses of branching filaments that replace many of the grains of the host plant.
The dried sclerotia of ergot, usually obtained from rye seed and used as a source of several medicinally important alkaloids and as the basic source of lysergic acid.
A fungus (Claviceps purpurea) that infects rye as well as other cereal grasses fed to livestock. Ergot forms sclerotia (masses of hyphae) that replace individual seeds in the spike of the infected plant and contain a complex mixture of alkaloids, several of which are medicinally important. Ergot is the basic source of ergotamine and lysergic acid. Ingestion of infected rye produces convulsions, hallucinations, and severe vasoconstriction that can lead to gangrene. Ergot poisoning may have been responsible for outbreaks of mass hysteria and reports of demonic visions in medieval Europe.