Hidden Giant Beneath Oregon: A Single Honey Fungus Spans 3.5 Square Miles
A single Armillaria ostoyae fungus under Oregon’s Malheur National Forest covers about 2,385 acres (roughly 3.5 square miles) and is estimated to be 2,000–8,500 years old, making it the largest known living organism on Earth. Its underground mycelium and rhizomorphs slowly kill trees to feed the colony, while the visible autumn mushrooms are small and transient. DNA fingerprinting and vegetative pairing proved the entire forest-wide network is one genet. There is no way to eliminate it; management focuses on planting resistant species and careful thinning to slow its spread.