Fantastic Fungi

The air shimmered as I walked through the forest, the heavy mists encompassing me in a damp blanket. As my shoes trod on soggy leaves, I took in the quiet serenity of the forest. Many of the trees had begun their annual changing of the colors, painting the canopy in shades of yellow, orange, red and green. Their discarded leaves were already beginning to dot the forest floor in late September. But fallen leaves weren’t the only contributors of color on the ground–the fall mushrooms were popping in the Northwoods.

A bright splotch of red and orange drew my gaze downwards, where a species of waxy cap mushroom was growing among the green blanket of moss. They are characterized by being very colorful, with a shiny, waxy looking cap, and thick gills. And unlike many other mushroom species, they are not mycorrhizal or saprobic. This means they don’t obtain their nutrients through extensive networks of mycelium that form a symbiotic relationship with plant roots, or obtain nutrients from decaying wood and organic matter like saprobic mushrooms. Waxy cap mushrooms are biotrophic, forming a symbiotic relationship with the roots of grasses and forbs, as well as the rhizoids of mosses, obtaining nutrients from them.

A brightly colored waxy cap mushroom growing up from the forest floor. 

Many other mushroom species inhabited the forest, making it come alive with fungi. Saprobic fungi in particular were very prevalent. Resinous polypores clung to decomposing trees, making it seem like the trees were growing pancakes dotted with maple syrup from their bark. Tiny Marasmius mushrooms sprouted from the top of a mossy log, their spindly brown stems and grooved white caps made my imagination run with thoughts of them being used as umbrellas by small woodland invertebrates. And even while my imagination ran wild with these fun fungi appearances, I was appreciative of the ecological role they play within the forest. As saprobes, they were breaking down the wood they inhabited and recycling important nutrients back into the soil.

Resinous polypores on a decaying log. 

But the wealth of different mushrooms carried with it many different feeding styles and ecological relationships. One complex and interesting ecological relationship that can be found in the Northwoods is between Entoloma abortivum mushrooms and honey mushrooms in the Armillaria genus. These fungi can be found grouped together in forests, and though they have an inconspicuous appearance, they are waging war beneath the soil. One of these mushrooms is parasitizing the other, disrupting the development of the other’s fruiting body and prohibiting them from reproducing.

Honey mushrooms in the Armillaria genus, have a brilliantly nefarious adaptation in regard to how they obtain their nutrients. They are both saprobic and parasitic. They infect their host, sapping its nutrients and eventually contribute to its death. Typically, this is the end of a parasite's ability to get nutrients from its host. However, since honey mushrooms are also saprobic, they continue to derive nutrients from their now dead host tree by breaking down the wood, and decaying the tree. This capability is called necrotrophism.

The other half of this fungal relationship, the Entoloma abortivum, are light grey, plain looking mushrooms that are typically found near decaying wood. While this mushroom's dull appearance may seem like a barrier to identification, Entoloma abortivum can at times provide a hint to its identity in the form of a lumpy, mass of white fungal tissue near the Entoloma’s fruiting body. This odd looking fungal body was originally thought to be an “aborted” form of the Entoloma, caused by a parasitic attack on the Entoloma as it was beginning to fruit.

Because honey mushrooms are parasitic, and are often found fruiting in the vicinity of the Entolomas, they were originally thought to be the aggressor in the Entoloma vs honey mushroom war. However, in 2001 a scientific study by Czederpiltz, Volk and Burdsall found the opposite to be true. They found that the “aborted” Entoloma were actually deformed honey mushrooms that were attacked by Entoloma abortivum hyphae– showing that the Entoloma is the parasite, not the honey mushroom! Since the parasitic attack happens underneath the soil, and involves both mushrooms' complex network of mycelium, there are times where the fruiting body of the honey mushrooms are not found near the Entolomas. But, with the presence of the “abortive entoloma”, we know that the honey mushroom mycelium is underneath the soil, but was parasitized by the Entoloma before it could fully fruit.

Entoloma abortivum and the "abortive entoloma".

It is amazing to me that a simple walk through the forest to see fall mushrooms can reveal so many ecological connections taking place. From stepping on soil that hides a vast network of mycelium, stretching out through the soil to obtain nutrients– to passing by a decomposing tree littered with saprobic mushrooms, slowly breaking the tree down and returning it to the soil. One can always find something to marvel at in the Northwoods, especially in the fall.

For more than 50 years, the Cable Natural History Museum has served to connect you to the Northwoods. Our Fall Calendar is open for registration! Visit our new exhibit, “Becoming the Northwoods: Akiing (A Special Place). Follow us on Facebook, Instagram, YouTube, and cablemuseum.org to see what we are up to.