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|I’d Call It That||3.0||14.20||3||(Christian Schwarz,convallaria)|
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It has to do with the fact that the mushroom in this observation is in the same genus. I now have to excuse myself from this conversation due to it being a colossal waste of time.
your summary seems to summarize your comment, too.
As for your discussion of CA-based Paxillus associated with birch: I don’t live there, and have never posted a comment about any CA-based Paxillus.
If we could try to stay on-topic, what does your CA-based Paxillus have to do with this obs. from Minnesota?
Chasing the shadow of reasonable doubt until it dissolves into a series of minor discrepancies (if they can even be given that much credit) is bad taxonomic practice.
Identification as Paxillus is supported by much visual evidence, and contested only by weak (which is to say variable and unimportant) and imaginary characters.
If we want to discuss something interesting, how about:
Assembling a publically-authored description for the very common but undescribed birch-associated Paxillus that fruits all throughout CA?
Or investigating how often (and which) EM fungi produce lignicolous-looking fruitbodiea?
Or noting that the closely related genus Paragyrodon produces fruitbodies with VERY prominent partial veils, and that maybe the presence/absence of veil remnants is maybe less important for generic identification (see recent Mycologia article on a veiled Pluteus variety from Europe)…
Or asking why the introduced birch-associated EM mushrooms in CA fruit months before most of the native EM fungi on the coast?
The obs. you cited has a centrally depressed cap. This obs. does not. Blow up the 5th photo and look closely. The cap is umbonate, not centrally depressed as in the obs. provided.
Where did we land on this one?
I don’t think we needed to rule out T. atrotomentosa. I don’t think anyone was considering that as an option.
But this does not match any Paxillus I can find reference to in NA. Are you suggesting it is a Paxillus from a different part of the world, perhaps SA?
That’s true. I don’t think anyone else was entertaining that notion.
In photos 2, 4 & 5, the stipe seems mostly central on this obs. Paxillus atrotomentosus stipe is “…usually off-center or even lateral…” according to Arora. And indeed your obs. Tapinella atrotomentosa (Batsch) Šutara (107561) seems similarly to have the stipe consistently off-center or on the side. Hard to tell precisely in this obs. because the substrate seems to be in the way.
If we are talking about T. atrotomentosa, the stipe doesn’t match in another important aspect: there is no velvety pubescens covering the bottom of the stipe. Look again at photos 4 & 5 here. It is conspicuous by its absence. Once again pointing away from Tapinella atrotomentosa (or Paxillus atrotomentosus in Arora).
What I see is an annulus. It is visible over 110 degree of the stipe, just below the descending gills. It may or may not extend further than that: we have just the one photo. If staining were caused by handling, I would anticipate greater discoloration then is visible.
I agree that growth on wood does not preclude identification as a mycorrhizal species.
There is no annulus on any of the mushrooms pictured. The upper left side of the third photo shows a brown smudge. The presence of the brown smudge is probably best explained by the fact that most Paxillus stain brown pretty readily.
Here’s an image showing a defined zone of coloration mid-stipe, which is pretty common for the genus Paxillus in my experience:
The gill that are wavy and slightly forked/anastomose, velvety cap surface cracking into fine plaques, and strongly inrolled and rounded cap margin are enough to call this a Paxillus with a pretty high degree of confidence.
veil in 3rd photo, upper left, other left side of stipe. Annulus also easily visible.
To Jason: mycorrhizal refers to plant-root/fungus interchange, not necessarily the mycelium (the fungal plant) which was probably found on the bottom of the log. In order to see mycorrhizae, it is necessary to use a microscope and see the host plant’s rootlet attachment as well. Most mycorrhizae are found in soil.
Growth on a log doesn’t preclude mycorrhizae. A well-rotted log offers nutrients and a water reservoir. Mycorrhizal fungi share water and nutrients with their host plant(s). Large woody debris becomes an important source of nutrients and water during droughts. (For more on this, see The Redefined Forest, by Chris Maser.) Some truffles (Hydnotrya) are especially found with large woody debris, and can be found on the inside of rotting logs, although they still require a host plant to survive.
Paxillus atromentarius, aka Velvet Pax in Mushrooms Demystified, I find on rotting old-growth conifer stumps fairly often. Paxillus involutus is a terrestrial mycorrhizal species I have grown with birch in my front yard. Arora lists P. pannnuoides as a wood-inhabiting: usually lacks stem and/or stalk and is fan-shaped.
This obs. has an annulus. Paxillus has neither a veil or annulus. Paxillus is therefor problematic.
On page 476 of Mushrooms Demystified under PAXILLACEAE: “VEIL and VOLVA absent.”
So if this has an annulus and veil, it is cannot be Paxillus, at least in NA.
Maybe a zone which darkened after being handled in some way.
I’ve seen Paxillus growing about 20 cm high from dead stumps (so really not looking mycorrhizal), so that doesn’t speak against it. The previously considered extremely variable species P. involutus has, afaik, been split into a bunch of hard-to-separate taxa, I didn’t even make an attempt to put a new species name on them.
Don’t think Paxillus has a veil, Christian. But I agree the overall appearance of this fungus certainly resembles Paxillus involutus, which in my experience is always mycorrhizal and terrestrial. Then again, I don’t believe I’ve ever seen a veil on one.
Created: 2012-08-30 16:53:31 PDT (-0700)
Last modified: 2012-09-02 16:21:40 PDT (-0700)
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