Armillaria ostoyae

Armillaria ostoyae, formerly known as Armillaria solidipes, is a pathogenic species of fungus in the family Physalacriaceae that infects trees and spreads underground through extensive mycelial networks rather than through visible surface growth alone. Its mushrooms have campanulate to convex, cream brown caps with prominent scales, decurrent gills, a ringed stem and white spore prints, and its mycelium can glow in the dark through bioluminescence, a phenomenon known as foxfire. The species grows in cooler regions of the Northern Hemisphere, especially in coniferous forests of British Columbia and the Pacific Northwest, infecting Douglas fir, true firs, pine and western hemlock. A single specimen in Oregon's Malheur National Forest spans about three and a half square miles, roughly two thousand two hundred acres, may weigh as much as thirty five thousand tons, and is considered among the largest living organisms on Earth by mass, area and volume; a separate Michigan specimen covers ninety one acres and weighs about four hundred forty tons, roughly the mass of three blue whales. The species is edible and considered a choice culinary mushroom despite its destructive effect on host trees.