Humongous Fungus, the world’s largest living organism

Honey mushrooms / honey fungus

The Blue Whale pales in comparison to this the size of this fungus in eastern Oregon.

Living in the Blue Mountains of Oregon, this humongous fungus occupies 2,384 acres (965 hectares) of soil, and it’s still growing. The fungus would encompass 1,665 football fields or nearly 4 square miles (19 square kilometers).

The fungus is generally referred to as the honey fungus or honey mushroom, which is actually a name given to several species of fungi in the Armillaria genus.

The mushrooms are safe to eat, although the name honey mushroom comes from its yellow-brown color above ground, not it’s flavor. Although some say it has a sweet aftertaste.

The discovery was made in 1998 when scientists began to investigate why many trees were dying in the national forest of Oregon. Root samples were taken from 112 dead and dying trees, which revealed that all but 4 were infected with the fungus. Furthermore, 61 of the samples were found to be genetically identical, meaning they originated from the same organism.

The discovery was helped by a technique used by the team. They paired fungal samples in Petri dishes to see if they fused, a sign that they were from the same organism.

This fungus, A. ostoyae, causes Armillaria root disease, which kills conifer trees in many parts of the U.S. and Canada. The fungus primarily grows along tree roots via hyphae. Hyphae are fine filaments that mat together and excrete digestive enzymes.

It also has the ability to extend rhizomorphs, flat shoestring-like structures, that bridge gaps between food sources, allowing the fungus to expand it’s perimeter more than other fungi.

Honey mushrooms / honey fungus

Based on its current growth rate, it is estimated to be 2,400 years old, but some estimate it to be as old as 8,650 years old, making it one of the oldest living organisms too.

A combination of good genes and a stable environment has allowed this fungus to continue to survive and grow for millennia. “These are very strange organisms to our anthropocentric way of thinking,” says biochemist Myron Smith of Carleton University in Ottawa, Ontario. “Collectively, this network is called the mycelium and is of an indefinite shape and size.”

The discovery of such as a huge specimen sparked a debate about what constitutes an individual organism. “It’s one set of genetically identical cells that are in communication with one another that have a sort of common purpose or at least can coordinate themselves to do something,” explains Tom Volk, a biology professor at the University of Wisconsin–La Crosse.

The mushroom’s we purchase in the supermarket may not be so small either. A large mushroom farm can produce 454 metric tons (1 million pounds) of mushrooms per year. “The mushrooms that people grow in the mushroom houses&133;; they’re nearly genetically identical from one grower to another,” Smith says. “So in a large mushroom-growing facility that would be a genetic individual—and it’s massive!”

It may be the case that massive networks of fungi are more common than we think, and we may even find another in the future that is even larger than this one.

“We think that these things are not very rare,” Volk says. “We think that they’re in fact normal.”