A parasitic fungal growth common to rye and several grains is, is ergot. Although history refers to a poison grain fungus as early as 600 B.C., it was not until the middle ages that ergot poisoning was graphically described. Epidemics of St. Anthony’s fire occurred following the ingestion of poisoned rye; entire populaces were driven mad, convulsive seizures were common, and pregnant women aborted. Intense vasoconstriction led to burning sensations in the extremities; gangrene was the ultimate fate. Meningeal and ependymal structures were affected by chemical products from the infected rye. Central nervous system symptoms noted in the epidemics resulted therefrom.

Erwin Lear, M.D., Chemistry and Applied Pharmacology of Tranquilizers. Charles C. Thomas, 1966.