Identified thirty years ago, this monstrous mushroom hidden in the lower parts of an American forest has just undergone new genetic analyses. The research has revealed an unsuspected property of the species Armillaria gallica – its gigantic size, which, according to estimates, can reach a weight of about 400 tons and spread over an area of nearly 370,000 square meters.
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Its presence in the lower parts of forests in Michigan, United States, was detected in 1988. That year, scientists surveyed the forest of the city of Crystal Falls in search of armillaria, a mushroom from the Physalacriaceae family often called ‘honey fungus’. They discovered a multitude of caps emerging at the foot of trees, onto which swarm the scientists decided to practice genetic analysis.
While studying the genome of these armillaria, the scientists were surprised to discover that it was, in fact, a real army of clones. All of them shared the same genetic heritage and were therefore part of a single organism, hidden in the forest’s soil: the infamous "monster" Armillaria gallica, a giant mushroom estimated then as weighing 100 kg and covering an area of nearly 120 square meters.
A revealing analysis
Recently, as part of a study that has just been published on Bioarxiv.org, an American-Canadian team of intrepid researchers has renewed the scientific investigation. They have once again visited the Crystal Falls forest, home of the original discovery, in order to confront the creature nicknamed ‘Humongous Fungus’. At least to its genome...
Thus these new genetic analyses revealed gigantism properties of this specimen of Armillaria gallica that surpassed everyone’s expectations. An estimation from 1988 places its weight at one hundred tons in 1988, but it is actually four times heavier, reaching about 400 kilograms, beating Earth’s biggest mammal, the blue whale, 170 tons at most on the scale, by a long shot.
A sprawling monster
The area Armillaria gallica occupies was also grossly underestimated thirty years ago. Far from the 120 square meters noted in 1988, researchers now estimate the giant mushroom’s surface at nearly 370 square meters. Needless to say, a monstrous being that still holds many other ‘immeasurable’ secrets...
Here are some of them. Back when it was first discovered, researchers thought it to be 1500 years old. In fact, that number is missing, give or take, a millennium. Second, its genome’s remarkable stability: of the 100 million bases that constitute it, only 163 have changed over the centuries of its uninterrupted growth. A monster in many ways, of course, but - one thing is certain – it is at least not a mutant!
To explain this unprecedented resistance to genetic mutations, the researchers have put forth several hypotheses. First, that of particular biochemical processes ensuring the stability of its genome. Another theory: the protection of this unusual organism through its essentially underground life, away from any mutagenic agent.
A record of gigantism ... but it still won’t go down in the Guinness Book of Records
Ultra-resistant, multi-centennial and excessively large, the Armillaria gallica from Michigan is still far from holding the world records for each of the aforementioned characteristics. The main competitor is a cousin, Armillaria ostoyae, discovered ten years later (1998) in the heart of the Blue Mountains range, in the state of Oregon.
Gallica practically looks like a youngling compared to Ostoyae - 8,500 years old, which is only a short time after the appearance of the first forms of civilization. Eighty-five centuries of growth at the end of which this specimen reached a surface of ... 9.65 square kilometers! This is more than any Parisian district. And all of this, from the capital famous for its ... mushrooms that pale in the face of the fungal monsters Armillaria discovered in the United States.
