No, it's not hipster Cthulhu. Known as "honey fungus," this huge underground organism is the world's biggest living thing. And its life cycle is incredible.

Photo of honey fungus by Stu's Images

The fungus lives largely underground, but it grows fruiting bodies above the soil that look like creamy yellow mushrooms. If you were picking one to sautée with your favorite pasta dish, you'd never guess that they were attached to a huge, ancient life form that occasionally preys on the Blue Mountain forest where it has lived for millennia.

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Over at the BBC, Nic Fleming tells the story of how the world's biggest honey fungus was first discovered in Oregon:

In 1998 a team from the US Forest Service set out to investigate the cause of large tree die-offs in the Malheur National Forest in east Oregon.

They identified affected areas in aerial photographs and collected root samples from 112 dead and dying trees, mostly firs. Tests showed all but four of the trees had been infected with the honey fungus Armillaria solidipes (previously known as Armillaria ostoyae).

When mycelia from genetically identical A. solidipes meet, they can fuse to form one individual. The researchers harnessed this ability, growing fungi samples in pairs in petri dishes. By observing which ones fused and which ones rejected each other, they found that 61 of the trees had been struck down by the same clonal colony ‚Äď individuals with identical genetic make-up that all originated from one organism.

The most widely-spaced were 2.4 miles (3.8 km) apart. The team calculated that the A. solidipes covered an area of 3.7 sq miles (9.6 sq km), and was somewhere between 1,900 and 8,650 years old.

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Below you can see an idealized illustration of how rhizome plants such the honey fungus grow.

The web-like network lives below ground, occasionally sprouting the fruiting bodies that look like mushrooms. What's so extraordinary about the honey fungus is that when two identical funguses meet, they can fuse to form a bigger organism.

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Yes, it's just as amazing and terrifying as it sounds.