Plicaturopsis crispa

December 19, 2022

Good evening, friends,
I teased it a bit last week, but this week’s mushroom is the Crimped Gill (Plicaturopsis crispa). I saw this mushroom for the first time this year on 10/25/2022, but have now seen it several times this fall. That includes during the Central Park walk we did in mid-November and extends to as recently as multiple times last week after the snow melted. From above this looks like several other species of shelf fungi you’ll see this time of the year, but when you check out the underside the identity of this mushroom reveals itself.

The identifying factor for this mushroom is the unique “gill-like” ridges on the underside of the cap. Technically not real gills, they’re more like the folds you’d see on Schizophyllum commune. Most other mushrooms that look like this (turkey-tail, other Trametes, and the smoother Stereum) have small pores or are completely smooth, but these pronounced ridges set this mushroom apart. All of the specimens I found up in Manitou have been growing on Sweet Birch (Betula lenta), but I think this mushroom may have been growing from black cherry (Prunus serotina) when we found it in CP.

One peculiar encounter I had with this mushroom was from earlier in the month when I found a rather patriotic smattering of colors on the white gill-like ridges. The red coloring below is fairly evident, but there was also a subtle blue tint to the ridges on the right below. The red growth didn’t look like a yeast or mold (or any other fungal organism attempting to digest this mushroom), so I dug a little deeper (i.e. read the comments on a mushroomobserver post), and learned about the bacterium Serratia marcescens. It is a fairly common and opportunistic species of bacteria that can infect both fungi and humans (remember fungi and animals are more closely related to each other than either of us are to plants or bacteria).

More is known about the bacterium in regards to it being a pathogen in humans where it’s commonly found in hospitalized adults and the digestive tracts of children. Likely it can be found in all of us, living as a mutualistic or benign microbe in our microbiomes (vast worlds of microrganisms that live on and within us). This specific bacterium causes illness or infection when one’s immune system or microbiome is out of equilibrium and can cause infection in several sites like the urinary and respiratory tracts. It can also be found outside of the body living in bathrooms where it creates a red film around toilet water lines or other surfaces, but it can also live in the soil.

Now where it gets really peculiar is the timing of the two most recent observations from MushroomObserver of this bacterium growing on mushrooms (References 3 & 4.) They were both from early December (the 1st and the 3rd) back in 2016 – one sighting in New Jersey and the other in Port Dover, Ontario. Well I happened to stumble upon this bacterium on December 2nd, 2022 – how about that? Open your eyes, folks, there is something much deeper going on here. Or, at the very least, we have to imagine this bacterium really likes the late fall as the other observations on the site were from October and November. This is why it’s fun to pick up sticks – you always get more than you bargained for.

Transitioning back to the fungal world, what’s also interesting about the above observation is that our mushroom, P. crispa, is growing on the same branch as what I’d say is its most common look-a-like, Stereum complicatum (goes by the common name “Crowded parchment”). S. complicatum has a very similar appearance when viewing the two mushrooms from above, but it’s completely smooth underneath and lacks any ridges or pores (below).

P. crispa is saprobic and grows from deadwood – particularly birches from what I’ve seen. It grows in the fall throughout forests in the Northern hemisphere. It’s considered an early-colonizer of dead wood and has been the first mushroom I’ve seen on fresh dead wood (almost an oxymoron) on multiple occasions. Those crowded, overlapping shelves below is the typical growth pattern for this mushroom. You can also see that the hemisperical caps aren’t just ridged underneath, but also feature some “crimping” when fleshing out from their narrow attachment to the wood. White spores are released from those gill-like folds underneath.

Next week might be a special holiday installment of MM, keep your eyes peeled. The days will be getting longer by then as the winter solstice is this Wednesday, 12/21. And a very Happy Hanukkah to everyone who celebrates,

3) Mushroom Observer observation 1:
4) Mushroom Observer observation 2: