Armillaria gallica

Armillaria gallica (synonymous with A. bulbosa and A. lutea) is a species of honey mushroom in the family Physalacriaceae of the order Agaricales. The species is a common and ecologically important wood-decay fungus that can live as a saprobe, or as an opportunistic parasite in weakened tree hosts to cause root or butt rot. It is found in temperate regions of Asia, North America, and Europe. The species forms fruit bodies singly or in groups in soil or rotting wood. The fungus has been inadvertently introduced to South Africa. Armillaria gallica has had a confusing taxonomy, due in part to historical difficulties encountered in distinguishing between similar Armillaria species. The fungus received international attention in the early 1990s when an individual colony living in a Michigan forest was reported to cover an area of 15 hectares (37 acres), weigh at least 9.5 tonnes (9,500 kg; 21,000 lb), and be 1,500 years old. This individual is popularly known as the "humongous fungus", and ......read more on Wikipedia.