To the left is the immature fruiting body of Armillaria (Armillariella ) tabescens, the root-rot fungus, a particularly aggressive parasite of living and dead deciduous trees. At this stage the mushroom features elongated stalks and small button-like caps. At maturity the fruiting body is soft and fleshy, not made to last long. In fact, although only a few days old, the mature colony often shows cracks on the pileus and sometimes breakage especially along the perimeter. In the photograph immediately below, note also the whitish dusting of the mushrooms by spores released from other mushrooms. Overarching caps have released large quantities of spores that have fallen onto the shorter caps.
After spore dispersal is accomplished, the mushroom rapidly breaks down into a gooey black mass that is soon to be consumed by herbivores like snails, slugs, tiny insect larvae and bacteria. Actually herbivory is often underway before this break-down phase (see below).
The many spores, of course, assure that there’s lots more root-rot fungus available to colonize the roots of the red maple and other susceptible trees (most often oaks) and produce next season’s mushrooms. This species and closely related ones in the genus are found in forested areas worldwide and are sometimes responsible for economically significant losses of timber because, unlike most fungi, they often attack trees while they are still living.Often these fungi operate as typical saprotrophs, degrading dead wood. The presence of colonies some distance from trees often occurs and usually signals the presence of buried wood.
Four photographs taken over a week of the same Armillaria colony: