Claviceps purpurea

Claviceps purpurea is an ascomycete fungus in the order Hypocreales, known as the ergot fungus. It infects the flowering heads of grasses and cereals, especially rye, but also triticale, wheat and barley, replacing the developing grain with a hard black survival structure called a sclerotium. That sclerotium, known as ergot, contains a range of ergoline alkaloids including ergotamine, some of which have potent effects on the human nervous and circulatory systems. Consumption of ergot contaminated grain causes ergotism, historically called Saint Anthony's Fire, an illness marked by burning sensations in the limbs, convulsions and in severe cases gangrene from constricted blood vessels. The link between ergot and grain poisoning was documented as early as the seventeenth century, and outbreaks of ergotism recurred across medieval and early modern Europe wherever contaminated rye bread was eaten. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/