Sac Fungi

A sac fungus and a slime mould

When hiking through the woods, I noticed this fungus growing on an old rotting stump. The way in which the fungus looks like the stump’s ear made me smile, and I stopped long enough to take a photograph. I touched the cup to get a sense of its texture. It was firm and rather rubbery.

My mycological expertise is limited to a few common species, but I recognised this cup-shaped growth as a sac fungus. None of the choices in my guide book, George Barron’s Mushrooms of Ontario and Eastern Canada, seems to match my find exactly, but it most closely resembles Humaria hemisphaerica. Correction: David William Fischer of AmericanMushrooms.com identifies this fungus as a Peziza species, likely P. praetervisa.

I was interested to read that sac fungi make up the largest division of all the fungi and are very diverse. Sac fungi are so named because the spores are produced in a sac-like cell, not because the fungi themselves are sack-shaped. The sac fungi include some very well-known members such as morels and truffles. Also included in this category is a species most gardeners recognise, powdery mildew (Erysiphe chichoracearum).

Under the cup fungus, you can also see clusters of small round orangy-brown dots. It’s a type of slime mold, probably a Hemitrichia spp. as per Mr. Fischer. Unfortunately, I didn’t notice it till I got home and looked at my photo of the cup fungus, or I would have tried to get a better photograph of the slime mould as well.

Powdery mildew on phlox leaves

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