In the late 1980s, researchers discovered the biggest organism on record, a “humongous fungus” on Michigan’s Upper Peninsula that covered 37 hectares, about the same size as the Mall of America in Bloomington, Minnesota. Now, the same team of scientists has found that this Armillaria gallica, which gives rise to honey mushrooms (above), is about four times as big—and twice as old—as they originally thought.
Like other fungi, Armillaria sprouts tiny threads underground; but unlike most fungi, these threads fuse to form shoelace-size strings that extend great distances to consume dead or weak wood. To find out how big the massive underground network of fungus really was, the scientists took 245 far-flung string samples and analyzed their genes. Not only did they belong to the same individual fungus, but—based on how fast the underground strands grow—that fungus must be at least 2500 years old, they report in a non–peer-reviewed study posted last week to the bioRxiv preprint server.