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Claviceps purpurea, ergot fungus


For many hundreds of years this highly toxic fungus, which finds a host in cereal crops, caused many thousands of deaths without anyone knowing of its existence.



Meaning of the Name

From the Latin ‘clava’, ‘club’ with the suffix ‘-ceps’, ‘-headed’ from its shape.

Common Names and Synonyms

ergot, ergot rust, ergot of rye, mother of rye

How Poisonous, How Harmful?

Ergot fungus contains a number of harmful substances collectively called the ergot alkaloids. Some of these alkaloids have been isolated and their effects studied but this page is concerned with the fungus, as a whole, not these individual alkaloids.

Ingestion of claviceps purpurea has three principal effects though the balance between them can vary from sample to sample.

Uterine contractions can be caused leading to miscarriage.

The blood supply to the extremities can be restricted leading to a burning pain in the hands and feet. This condition is one of those called 'St Anthony's Fire' and can lead to gangrene which, if untreated by amputation, may be fatal.

A third of the ergot alkaloids is a close relative of LSD and is, therefore, strongly hallucinogenic.

In the days before the recognition of the effects of the fungus and moves to prevent it entering the food chain, outbreaks of ergot poisoning would occur regularly resulting in thousands of deaths. These outbreaks seem to coincide with very wet summers; the fungus thriving in wet, warm conditions.


Modern control methods are designed to prevent ergot fungus, which forms on rye and, to a lesser extent, wheat, from entering the food chain via bread products but there are, still occasional outbreaks.

The true cause of the outbreak of poisoning in the French village of Pont-Saint-Esprit in 1951 has never been fully explained but ergot-like alkaloids remain the most likely culprit.

My own view is that, although it is very unlikely that a firm conclusion could ever be reached, the most probable cause was Aspergillus fumigatus not Claviceps purpurea.

A full discussion of the evidence I have read and the conclusions reached is now on a page about Aspergillus fumigatus.

Folklore and Facts

Outbreaks of ergot poisoning occurred frequently in mediaeval times, especially in a damp year when the fungus could thrive. The most common effect was the constriction of the blood vessels producing a burning sensation in the limbs, known as St Anthony’s Fire. This name was applied because many victims recovered after a pilgrimage to St. Anthony's shrine. It is now known that removing a victim from the source of the fungus leads the condition to abate. Without this knowledge and without the money to undertake a pilgrimage, many victims developed gangrene resulting in the need for amputation. It was these amputations which formed a large part of the surgery performed at Soutra Aisle, south of Edinbirgh, where a mixture of hemlock, henbane and opium poppy was used as a sedative to keep patients asleep for up to 96 hours after the trauma of the operation.

Ergot fungus has been used to try and explain strange historic events. It has been suggested that the initial accusations of witchcraft made in Salem, Massachusetts, which became the subject of Arthur Miller's play 'The Crucible', were made by women suffering hallucinations after ingesting ergot. Mass hysteria then produced the full traumatic events.

Ergot has been offered as one possible explanation of the mystery of the 'Mary Celeste'. In this version of the story, the ship was supplied with contaminated wheat for the galley and the entire crew suffered ergot poisoning. Driven mad both by the ergot and the burning pain in their extremities they decided to jump into the sea to quell the flames of St. Anthony's Fire.

Lack of scientific evidence can lead to substances being implicated in incidents without any justification. The Dancing Plague of Strasbourg in 1518 is sometimes said to have resulted from ergot poisoning but the symptoms displayed by the victims do not match any of those associated with the ergot alkaloids, other than the mental distress. John Waller believes it to have been mass hysteria.

There is also the bizarre story which is said to be recorded in the ‘official medical records’, whatever they are, of a woman suffering from the gangrene which ergot poisoning can cause. She was riding a horse to hospital to have a leg amputated when the horse brushed against a bush by the side of the road causing the leg to fall off.