In the mixed-conifer forests of the Blue Mountains of northeastern Oregon there lives an organism that makes the massive African bush elephant and even the gargantuan blue whale seem petite by comparison. In fact, it is the world‘s largest single living organism.
That would be Armillaria ostoyae (AR-mill-air-ee-yuh ahst-oy-ee), or, as some like to call it, Oregon‘s humongous fungus. It‘s an apt nickname for an organism that covers 2,384 acres of land.
1600 Football Fields
To put that in a different perspective, this fungus could encompass over 1600 football fields in its behemoth expanse.
You're probably wondering, "How can we be sure that Oregon‘s humongous fungus is truly a single organism and not a cluster of smaller ones?"
And that‘s because the fungus has one set of genetically-identical cells that communicate with one another and indicate common purposes, or coordinated activities. By that definition, both the blue whale and Armillaria ostoyae are considered single organisms.
Honey Mushrooms
All fungi of the Armillaria genus display so-called "honey" mushrooms, which have yellow caps and sweet-tasting fruiting bodies. These only represent the sexual phase of the fungus‘s life.
Long, microscopic filaments called hyphae connect these fruiting bodies; together they form thick, white mats called mycelium that can grow to immense sizes. This is the vegetative phase.
As the mycelium grows, the individual hyphae secrete digestive enzymes that break down and decompose their food. Sometimes, with this particular fungus, that can mean starting at the roots and killing the tree.
Armillaria ostoyae grows ever bigger. The more we learn about fungi, the more we realize that perhaps colossal size is not rare for them.
The Armillaria ostoyae is one of the oldest living organisms on Earth, if you want to learn more about another very old living animal, click here to read about the Greenland Shark. If you want to learn more about how fungi systems interact with forests, click this link.
Thank you to M. Catherine Aime of Purdue University for reviewing this episode's script.