November 7, 2022
Good evening, friends,
This week’s mushroom is the convivially named Plums & Custard (Tricholomopsis rutilans). I found this mushroom at the base of a dead hemlock tree while hiking along the Appalachian Trail in Hopewell Junction, NY on 8/15/2022. This handsome mushroom’s penchant for dead conifers should make it happy in the northeast where the hemlock woolly adelgid has created an abundance of dead hemlocks.
The peculiar common name, Plums and Custard, is derived from the plum colored cap and the custard yellow gills. Unfortunately it’s not as tasty as the name suggests, but people have allegedly consumed the mushrooms after boiling them in water for a short period of time (known as parboiling) before finishing them in a skillet. Folks will prepare honey mushrooms in a similar manner, but this culinary technique starts to tip the scale on the effort vs payoff matrix for eating dinner. How much effort do you really want to exert to make dinner? You start to stack the dishes up when you’re boiling and sautéing. When I nibbled the cap and spit it out I noticed the distinct taste of red beets. Other references have alluded to these mushrooms tasting like radishes, so they certainly have a earthy, mealy flavor.
The species name “rutilans” is derived from the latin Rutilus which means red – a nod to that plum colored cap. The suffix –opsis comes from ancient Greek and is used to denote that the organism bears a resemblance to whatever prefix/name precedes it. So Tricholomopsis means that they bear a resemblance to Tricholoma mushrooms. Other common names for the mushroom include the “variegated mop” and the “red-hair agaric”.
DNA sequencing suggests that the North American species of T. rutilans is a genetically distinct species from the European T. rutilans. A study from the good folks over at King Juan Carlos University in Spain found five genetically distinct species of T. rutilans after sequencing collections from Europe and North America (Reference 2). They weren’t able to get enough information to nail down a distinct North American species and said more research is needed to do so. They did, however, identify a species (Tricholomopsis pteridicola) that is found only in the Pyrenees and associates with eagle ferns. This is an example of one feature of fungi that absolutely fascinates me. Two mushrooms can look exactly the same but then DNA sequencing reveals they are genetically distinct species. In many instances the only difference is their geographic distribution. We can then ask how much does it matter that the Plums and Custard in Europe is genetically distinct from the Plums and Custard in North America? Probably not much at all for enthusiasts like us.
T. rutilans is saprobic and digests dead conifer wood, but in rare circumstances it will pivot preferences to decompose deciduous wood. It grows spring through fall in the northeast (particularly in the fall) and the full iNaturalist distribution chart is below. It’s likely this map is an aggregate of the five different genetic species we touched on earlier. An important identification characteristic across all the P&C mushrooms is that white ring where the stipe meets the cap (seen above). The cap and stipe are both yellow but are coated with those conspicuous maroon scales. The gills, which are spaced quite close together, are also yellow – however the spores released from them are white.
Central Park Walk
This Sunday, 11/13, at 10AM in the Ramble. Same meeting place as always, by the toolboxes on the west side of the Ramble (see the blue pin below). The foliage should be prime and we may get some rain the day before so we can hopefully see some more ephemeral species that pop up right after rain. See you then and let me know if you have any other questions.
Tomorrow morning, 11/8, there’s a Blood Moon lunar eclipse (meaning the moon will appear a dark, blood red). The eclipse will peak right around 6AM. It’s the last total lunar eclipse until 2025 so it might be worthwhile to set the alarm,
PS. A lot of diligent googling goes into producing these emails and during that research I stumbled on an old internet post that featured a mushroom growing from a mop. Looks like something from the genus Coprinus, a decomposer. Check it out: https://www.reddit.com/r/mildlyinteresting/comments/zv49n/a_mushroom_growing_on_a_mop/
1) Kuo, M. (2020, February). Tricholomopsis rutilans. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/tricholomopsis_rutilans.html
2) Olariaga, Ibai & Gonzalez Laskibar, Xabier & Holec, Jan. (2015). Molecular data reveal cryptic speciation within Tricholomopsis rutilans: description of T. pteridicola sp. nov. associated with Pteridium aquilinum. Mycological Progress. 14. 10.1007/s11557-015-1040-4. Online: https://www.researchgate.net/publication/275252073_Molecular_data_reveal_cryptic_speciation_within_Tricholomopsis_rutilans_description_of_T_pteridicola_sp_nov_associated_with_Pteridium_aquilinum