Phaeotremella frondosa

Good evening, friends,

We’re keeping it gelatinous this week and looking at another jelly fungus, Phaeotremella frondosa. This mushroom doesn’t have a common name (yet, but keep reading), although the nearly identical Phaeotremella foliacea is called the “Leafy Brain” which is appropriate. I encountered this mushroom twice last week during that interminable stretch of rainy days and overcast conditions. While this mushroom looks like just another decomposer, there’s a lot more going on inside the log than we would gather at first glance.

Fun Facts

This fungus is parasitic on fungi in the genus Stereum. You’ll notice Crowded Parchment (Stereum complicatum) growing in near proximity both above and below. I would love to get a microscopic view of the Phaeotremella mycelium tapping into the Stereum mycelium - I’m curious how they originally discovered the relationship between the two.

Notice the variation in color between this specimen and the first picture. Age, temperature, moisture, and other environmental conditions can impact the color of this mushroom (and basically any mushroom for that matter).

This fungus used to be in the genus Tremella, which means “to tremble” and refers to the gelatinous composition of the fruiting body. Recently, DNA sequencing created the new genus Phaeotremella. The prefix Phaeo- means “dark colored”, so all together we get a “dark colored trembling mushroom”. Pretty accurate. The species epithet frondosa comes from the latin frondis which means leaf/foliage and refers to the leaf-like appearance and composition of the individual lobes of the mushroom.

Interestingly, the genus Tremella was one of the original genera created by Carl Linnaeus and at the time he grouped these mushrooms in with algae and seaweed. This was long before fungi were separated from plants. That said, “Seaweed of the Woods” has a nice ring to it. It’s provocative, it makes you want to ask questions. Since “Leafy Brain” refers to the sister species Phaeotremella foliacea, I think we could make this mushroom’s Monday if we endowed them with a cool common name.

Ecology

As previously noted, the fungus is parasitic on the mycelium (the body) of Stereum, but not the actual fruiting body (the mushroom). You can find Phaeotremella wherever you find Stereum (which digest a variety of hardwoods). P. frondosa sightings peak from October through January on iNaturalist. This fungus likes to fruit in colder temps and can be found throughout temperate regions of the northern hemisphere.

I've been watching one seaweed of the woods for a few weeks now and just checked it this morning (it was frozen). The mushroom hasn't changed much in size, but I did notice a pile of goop at the base of the tree, beneath the mushroom. Perhaps parts of the mushroom fall off and new lobes erupt from the tree to replace them. It didn't look like the goop had originated from another point further up the tree, but that could be a possibility too.

The aforementioned sister species, Phaeotremella foliacea, is found on conifers (evergreens) which is interesting since the fungus supposedly gets their nutrition from Stereum, and not the wood. Perhaps the coniferous Phaeotremella is specialized to parasitize Stereum that digest conifers.

Further, it’s unclear if the Phaeotremella causes any negative effect on the Stereum, and Stereum complicatum is usually fruiting heavily whether or not the parasite is present. Like last week’s Exidia, there’s a lot more research left to be done with these jelly fungi, but for now we can touch, smell (no odor), and wonder about their relationship with the other fungi in the wood.

The goopy, frozen specimen above two weeks ago. Lighter in color and more hydrated.

A monstrous thank you to everyone who signed up for Mushroom Monday premium. You put your faith in me and I won’t let you down. The first blog on beavers will be out later this week. I already went out and visited them a few times this past week so here’s a little teaser to whet our appetite.

Lunar New Year this Saturday, get ready to welcome in the year of the Dragon,

Aubrey