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Black Sooty Mold - Scorias spongiosa

Good evening, friends,

This week we're looking at a fun little fungus, Scorias spongiosa, commonly known as Black Sooty Mold. I found it growing on an American Beech tree (Fagus grandifolia) while poking around Clarence Fahnestock State Park yesterday. There's a substantial overlap in the Venn diagram of fun facts and ecology in today's publication. This means if you're a picture person that has at times found yourself considering a read of the ecology section, well you won't be sorry if today is finally the day.


Scorias spongiosa

Fun Facts

When taking pictures of mushrooms/fungi, it's typically best to take photos of the specimen in the shade - using your own body or calling for back-up if need be. Due to the time of day and the location of the mold on the tree this wasn't feasible, so these pictures are saturated with sunlight. Undaunted, we proceed.


If these pictures weren't already making you hungry, you'll be relieved to know that yes, S. spongiosa is edible. In fact, polysaccharides (sugars) in the fungus were found to have anti-inflammatory and anti-oxidative effects on the guts of mice. This resulted in a greater biodiversity in the gut microbiome for said mice relative to the control (Xu et al, 2022 - reference 2). This specimen was hard and crusty, not the most appetizing. However, the texture of the fungus when young is spongy which I imagine lends itself more to ingestion. I'm curious as to what a tea of this crusty specimen might taste like - I'll report back next week.


Scorias spongiosa

Ecology

How did these black growths get on this Beech tree, you ask? Well it's a peculiar process. It starts with an aphid - a tiny insect that sucks sap from plants. Some aphids are generalists, sucking the sap from a variety of different plants, but the beech blight aphid (Grylloprociphilus imbricatur) exclusively sucks the sap from American Beech trees. Here's a photo of these aphids from the Ohio State's Buckeye Yard & Garden Online:


Aphids on hand and plant

The aphids group together on the trees and excrete a sugary waste byproduct politely called "honeydew". We're talking about poop here, folks. S. spongiosa, an ascomycete, grows on this honeydew. It grows too much larger sizes than its relatives due to the high sugar content and concentrated proximity of the food source. The fungus doesn't do any harm to the tree, other than perhaps restricting some photosynthesis, but it's been shown that the honeydew and fungal growth on the forest floor hinder beech nut germination - an indirect impact on the regeneration of beech trees (reference 5).


The aphids have two reproductive cycles during the year, and the largest excretions of honeydew are produced by the second generation of aphids in September and October. At that time, the fungus has an olive color, spongy texture, and produces asexual spores. Later in the fall, physiological changes lead to the production of sexual spores along with the darkening of the fungus to the black soot we see here.


Scorias spongiosa

I've been searching for morels to no avail, but I didn't get skunked today. Here's what I'm lead to believe is Disciotis venosa:



I visited Central Park on Saturday and was surprised to see that it's easily a week and a half further into spring than up here in Manitou. The Trout Lily (Erythronium americanum) up here is just starting to bloom where as it had already gone to seed down there,

Aubrey


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