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Red-Cracking Bolete (Xerocomellus spp.)

Good evening, friends,

This mushroom comes to us as a pleasant surprise. Saturday morning we went for a quick walk in the woods to find a few fresh specimens for the mushroom education workshop in Peekskill. Although it had rained the day before, I wasn’t anticipating too much fungal activity because it has been pretty dry the past few weeks. Fortunately, Ciara pointed out this brown capped bolete popping out of the soil just beneath a rotting hemlock. This was the first bolete I’ve seen this year and one we’ll tentatively call the Red-cracking bolete (Xerocomellus spp).


The.red scratches on the top of the cap - maybe from an insect or someone/something trapped in the wood desperately trying to get out - are a helpful identifying characteristic.
The.red scratches on the top of the cap - maybe from an insect or someone/something trapped in the wood desperately trying to get out - are a helpful identifying characteristic.

Fun Facts


The species you’ll often see attributed to the Red-cracking bolete is Xerocomellus chrysenteron, and while that used to be the nomenclature in North America, modern DNA sequencing indicates it’s a European species. Xero- means dry while chrysenteron means “yellow inside”. In eastern North America we have a species that is virtually identical by the naked eye, Xerocomellus truncatus, but reveals truncated spores when observed through a microscope. Unfortunately, I wasn’t able to manipulate this mushroom too much - no ripping, tasting, nor cutting - because it needed to be in good shape for the ID table.


A study out of the Czech Republic (Reference 3) looked at the different elements that are absorbed by the European X. chrysenteron. Interestingly, these mushrooms absorb heavy metals like Silver, Cadmium, and Rubidium - see gang, mushrooms are metal🤘. Even more interestingly, there was a difference of where these metals concentrate within the mushroom. Silver, Arsenic, Cadmium, Copper, and Sulphur accumulate in the “apical parts” - the cap and tubes - more-so than the stipe and base.


Red-Cracking Bolete (Xerocomellus spp.)
Red-Cracking Bolete (Xerocomellus spp.)

If you rip the cap of a Xerocomus or Xerocomellus mushroom in half, the tubes of the mushroom will actually rip lengthwise as well. Typically, if you were to rip the cap of any other bolete, the walls of the individual tubes would remain in tact while the tubes were separated from each other. The difference in structural integrity is due to the different compositions of the hyphae (filamentous strands, the body of the fungus) in the mushrooms.


When you see the temperatures forecasted for the rest of the week.
When you see the temperatures forecasted for the rest of the week.

Ecology


Xerocomellus are ectomycorrhizal with hardwood trees. This means the fungi wrap around the root tips of the trees and establish a relationship where the tree will give up to 40% of sugars produced through photosynthesis to the fungi in exchange for nutrients and water the fungi sources from the soil. The mushrooms pop up late spring through fall in eastern North America, and these are fairly common mushrooms that will grow individually or in clusters.


Another study from Europe, this time out of Belgium, looked at ectomycorrhizal turnover in growing European beech trees. Xerocomellus (along with Lactarius, Laccaria, and Scleroderma) appear to be important in helping seedlings establish. Xerocomellus was also found more abundantly in young forests adjacent to older forests which suggests they readily colonize young trees and will form long-lived relationships. The study concluded that a tree will partner with different fungi at different stages of life - from seed to sapling to mature tree - based upon their needs at the time. There’s so much more going on in the soil than we know.


The blue bruising on the pore surface is seen in many boletes across many different genera.
The blue bruising on the pore surface is seen in many boletes across many different genera.

Solstice on Thursday and full moon on Friday,

Aubrey


References

  1. Kuo, M. (2024, March). Xerocomellus "chrysenteron". Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/xerocomellus_chrysenteron.html

  2. Bessette, Arleen, et al. Boletes of Eastern North America. Syracuse University Press, 2017. Pages 414-417

  3. Andronikov AV, Andronikova IE, Sebek O, Martinkova E, Stepanova M. Accumulation and within-mushroom distribution of elements in red cracking bolete (Xerocomellus chrysenteron) collected over the extended period from compositionally contrasting substrates. Environ Monit Assess. 2023 Sep 6;195(10):1157. doi: 10.1007/s10661-023-11786-6. PMID: 37673806; PMCID: PMC10482781.

  4. https://www.inaturalist.org/taxa/416305-Xerocomellus

  5. Boeraeve M, Everts T, Vandekerkhove K, De Keersmaeker L, Van de Kerckhove P, Jacquemyn H. Partner turnover and changes in ectomycorrhizal fungal communities during the early life stages of European beech (Fagus sylvatica L.). Mycorrhiza. 2021 Jan;31(1):43-53. doi: 10.1007/s00572-020-00998-0. Epub 2020 Nov 2. PMID: 33140217.

  6. https://www.first-nature.com/fungi/xerocomellus-chrysenteron.php

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