This confocal micrograph shows wheat stigma hairs (blue) infected with ergot fungus (shown in light pink). The stigma hairs are part of the female reproductive organs of the plant. When a pollen grain (released by the male reproductive part) adheres to a stigma, a pollen tube grows and fertilizes the plant's ovule. Ergot is a type of fungus from the genus Claviceps that infects flowering grasses and cereals, including wheat, by mimicking the growth of pollen into the ovary. The fungal hyphae, shown in pink, highlight the path the fungus takes through the stigma hairs to colonise the whole plant flower. The fungus forms a dark, purplish sclerotium (a dense mass of branched hyphae) called an ergot in place of the developing wheat grain. Ergot is highly toxic. If infected plants are eaten it causes ergotism, with symptoms that include spasms, hallucinations, psychosis, itching and gangrene. Ergot poisoning is one of the suggested explanations of bewitchment. In the Middle Ages, monks of the Order of St Anthony were known for treating this condition, and the illness became known as St Anthony's fire.