She identified the fungus through DNA testing. Then, by comparing cultures of the fungus grown from the 112 samples, she determined that 61 were from the same organism, meaning a single fungus had grown bigger than anything anyone had ever described before. These are mats of mycelium, which draw water and carbohydrates from the tree to feed the fungus and interfere with the tree's absorption of water and nutrients. The long rhizomorphs that stretch as much as 10 feet into the soil invade tree roots through a combination of pressure and enzyme action. The huge size of the fungus may be related to the dry climate in eastern Oregon, Dreisbach said Friday.
Spores have a hard time establishing new organisms, making room for the old-timers to spread.