From hallucinations to seizures, limbs lost to gangrene, and the theoretical evolution of fungal zombies, a tiny fungus that inhabits some grain species has a long history alongside humans. Ergotism, a long-term form of ergot poisoning, is a dangerous condition caused by the ingestion of a small fungal growth that replaces the seeds of some grass species, especially those cultivated by humans. This has numerous horrible side effects on any animals that consume the fungus, but is, of course, most well-known in humans. This leads it to have some surprising historical implications. 

With over 50 known species, the genus Claviceps has evolved to infect a wide variety of grasses. These fungal bodies most often infect ryegrasses, but various species can also infect wheat, barley, and on rare occasions, oats. Like any other fungus, Clavicerps start as spores; these infect the florets of flowering grass species, such as rye and wheat. Once inside the floret, the spore grows to develop mycelium, the main body of the fungus. Once this mycelium forms, it destroys the flower and latches onto the vascular bundle that would normally provide nutrients to a fertilized flower, producing seeds. Thus, it begins to grow into a fruiting body–a mushroom of sorts–known as an ergot sclerotium. This ergot resembles just another seed of the grass, often only differentiable by brown, black, or grey coloring, as seen in the wheat below. This mimicry causes the fungus to often be overlooked in processing grains for agricultural production. Yet, some species of Claviceps do grow a more distinct fruiting body, such as that of Claviceps purpurea, seen growing on a head of barley below. 

Left: Ergots growing on a head of wheat. Right: Claviceps purpurea growing on a head of barley. 

With that in mind, ergot poisoning can be very serious. As mentioned before, prolonged poisoning can lead to a deadly condition known as ergotism, which can mean gangrene in one’s limbs due to reduced blood circulation, causing the limb to need to be amputated for risk of the rot spreading. Furthermore, some other aforementioned symptoms of ergot poisoning include hallucinations, seizures, extreme fever, inability to speak, manic episodes, paralysis, and more. All of these are only worsened when the poisoning becomes ergotism, making it virtually incurable: a death sentence. 

The most common form of ergot poisoning, St. Anthony’s Fire, causes a violent burning feeling, extreme fever, peripheral flashes, and shooting pain in one’s extremities. Although the least serious, it can still becomed deadly ergotism. 

No matter the initial result of consuming the ergot, it often leads to a violent and painful death. This is because of the alkaloids produced in the fruiting body of the Claviceps genus, which are extremely effective in attacking our body, especially our brain. Considering this, seeing as the cultivation of grain is central to a large portion of humanity’s food supply, breakouts of ergot poisoning have been seen across history.

The earliest known specimen of an ergot-like fungus was found on a grass encased in amber: dated to be over 100 million years old. Likewise, ergot poisoning is the oldest known form of reactions to toxic molds and is referenced as far back as 600 BC: an Assyrian tablet that has a description that aligns with that of ergot fungus. Ergotism became extremely prevalent in Medieval Europe, with some outbreaks racking up tolls of nearly 40,000 dead. Such outbreaks are still seen today, mainly in regions near the equator, as the conditions of high humidity and warm temperatures, the ideal climate for ergot growth, are most stable there. 

Even so, one theory states that the hysteria that resulted in the infamous Salem Witch Trials may have been caused by ergot poisoning. Mania, convulsions, hallucinations, burning skin, stabbing pains in extremities, all symptoms of ergot poisoning, and all recorded in “victims” of the witches of Salem, Massachusetts. Even though rye was common in the area and the climate at the time created prime conditions, this theory is strongly refuted by some scholars, yet supported by others. Either way, it is an interesting theory and leads to questions of how else this fungal infestation might have affected humanity’s history, and how it may be in the future.

A “clicker”, an advance form of the cordyceps infection.

Theories of how Claviceps may impact our future have arisen over time, and recently this topic has gained a lot of attention thanks to HBO’s newly released adaptation of the game series “The Last of Us.” The series involved a fungal virus known as cordyceps, seen above, that evolved from what seems to be Claviceps, combined with Orphiocodyceps, a fungus that is well known for how it infects insects and turns them into “zombies.”  It does so by taking over the insect’s brain, gaining function of its body for a time before killing it, and using the body as food while growing a fruiting body to spread spores. In the series, this combination created an epidemic of worldwide proportions, as the fungus that began in grains from crops near the equator quickly spread from human host to human host, and evolved more as it spread. Although fantasy, such an idea isn’t too far-fetched with how we understand the ways fungus affects the human brain, from hallucinogenic mushrooms to ergots. If this topic interests you, one suggested documentary is “Fantastic Fungi” on Netflix. 

From ancient Assyria to theoretical epidemics, Claviceps has been the cause of numerous outbreaks of hysteria, accusations of witchcraft, and extensive deaths, all from a small fungal body in grains, known as ergot.