Observation 92860: Agrocybe Fayod
When: 2012-04-13
No herbarium specimen

Notes: with Douglas fir and Western hemlock.

Species Lists


spores in 5% KOH @ 800x
cellular structures in the context
cells in the pileus.
context or cuticle? corrections welcome.

Proposed Names

-29% (3)
Recognized by sight
54% (4)
Eye3 Eyes3
Recognized by sight

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Eye3 = Observer’s choice
Eyes3 = Current consensus


Add Comment
about the spores
By: Britney Ramsey (Riverdweller)
2012-04-18 16:30:53 CDT (-0400)

here’s what Mushroom Expert has listed.
“….Microscopic Features: Spores 11-15.5 × 5-6.5 µ; elliptical, but with a “snout-like” end; smooth."
Not really present here.

I’m loading the new microscopy of the cap.

Sure, go for it.
By: Douglas Smith (douglas)
2012-04-18 14:07:54 CDT (-0400)

Have you dried this one? If you dry it well, then put it in an air tight stiff container, it will keep for years, and you can study it when ever. But this seems more of a learning opportunity than an important specimen here really.

But with these questions of genus, really the most important feature to look for is the cell structure of the cap surface. The top most layer, or few layers of cells, this is called the pileipellis. This is really a defining character for many genera, more than cystidia and spores, which are more specific characters. And dna work has shown this to be true also.

Anyway, I usually take a “radial section” of the cap, take two parallel cuts, from the cap margin, slicing in towards the center of the cap, and make them as close together as possible. This should give you a thin slice of cap material showing the fertile surface of the under-side on one side, and the cap surface on the other end of the slice.

For Agrocybe the cap surface should be a single layer of mostly upward facing cells, sometimes globose, sometimes finger-like, like upward pointing fingers, and usually covered in a layer of gelatin. For Psathyrella there should be several layers of globose cells, without any gelatin, sometimes with some very thin long hyphae at the very surface.

That will give you more info here, and fun making sections, and looking for the important characters for id to genus at least…

Happy to mount another slice and document it here.
By: Britney Ramsey (Riverdweller)
2012-04-18 13:40:21 CDT (-0400)

I will get to that this afternoon.

about the mount.
By: Britney Ramsey (Riverdweller)
2012-04-18 13:37:12 CDT (-0400)

I sliced a piece off that had the gills, context, and pileus. Keeping the cap on the left and the gills forking to the right is my habit when I prepare the slide. It’s not crush mounted and it doesn’t have a cover slip. Just the tiniest slice I can manage arranged in the above described fashion with a drop of KOH. Those globose cells were at the very outer edge of the slice on the left side of the slide. I had some trouble understanding what names to call each type of cellular structure, but I’m certain on what I was looking at.
The gills were what had me convinced in the field that this was a Psathyrella. The cap dried like a Psath also. When I first loaded the micrographs I was still convinced of Psathyrella but couldn’t find any argument against the conversation about the stem and the annulus.

The observation suggested as a good comparison to this one and in support of Agrocybe erebia looks similar to mine in microscopy, but not in overall general appearance.
Another thing, about those gills, I saw no interveining in the gills, as described here:
“… adnate to +/- decurrent, subdistant, broad, interveined; pale brown then rust brown, (Hermanson), attached to slightly decurrent, close to subdistant, often interveined, pale brown becoming dull brown at maturity, (Bessette)”

Also, no rust colored gills. They are a chocolate brown color.

Having said all that, I don’t know which to support. I will change my vote to reflect that better.

I still have this and it’s in pretty good shape still. Can I revisit this under the scope and provide more clues?

By: Douglas Smith (douglas)
2012-04-18 12:43:06 CDT (-0400)

Not to add problems to the discussion here, but in the last two shots you show layers of globose cells. This looks like an epithellium, which would make this a Psathyrella not an Agrocybe. But I’m not sure how carefully you have made the mount there, and if we are really looking at the surface cells.

By: Britney Ramsey (Riverdweller)
2012-04-18 09:58:23 CDT (-0400)

I have a Celestron digital touch screen right now, but I’ll be buying something more powerful soon. It’s been a good little starter scope to learn with.

Cool photos.
By: Kari (Kari)
2012-04-18 03:28:49 CDT (-0400)

Love your spore & cystidia shots. What type of microscope do you use? I’m currently on the prowl for one of my own, can’t wait to get into microscopy too :o)

thanks everyone
By: Britney Ramsey (Riverdweller)
2012-04-17 13:12:15 CDT (-0400)

I like when the convo flows…I learn so much! Seriously, I love MO and it’s been my college of sorts these past two years.

Bloodworm, I changed my labels to match your suggestions. Thanks for that. Now if I could scrounge up the duckets for a scope like yours…..your microscopy and studies really impress me and I’m glad you’re hooked like I am!

Irene and Deb, thanks for taking the time with this one and supplying links and discussion. I was flying blind on this one and I still don’t feel ‘connected’ to the results if that makes sense. I’m just nodding yes because I trust your experience and reading what I can about A.erebia. :)


I thought that we all…
By: Debbie Viess (amanitarita)
2012-04-17 12:29:40 CDT (-0400)

have one foot in the future here on this list! ;)

My point being, Psaths in their true and broad sense have a delicate stipe, very unlike this mushroom. Of course, there are exceptions to the rule in every group, and there is a Psath with a membranous ring, too: longistriata. But this ain’t it.


Funny about the word peronate, though…the top photo shows a mushroom with an annulus that points up. When a sheathing veil breaks, the remains/annulus also points up. Somehow, the definition of peronate, when I first learned it in relation to Agaricus sp., came to mean in my mind an annulus that points up. Obviously, the truer definition of peronate is a sheathing veil.

I sit corrected!

Britney’s lower photo of this Agrocybe shows an annulus that has been handled post-extraction, and is no longer pointing up; I never got that far, though.

All of these characters, including an up-pointing annulus, seem to match up with Agrocybe erebia pretty darned well, assuming that everything being called erebia here actually IS erebia….another can ’o worms. But Irene knows the micro, and the micro fits, too.

Carry-on, taxo-buddies. Debate is good.

By: Richard and Danielle Kneal (bloodworm)
2012-04-17 09:51:49 CDT (-0400)

i believe your pleurocystidia is actually cheilocystidia and your 7th picture is probably pileipellis.

I can’t see the size
By: Irene Andersson (irenea)
2012-04-17 03:48:28 CDT (-0400)

but the shape of spores and cystidia is a perfect match with Agrocybe erebia.
The striped (gill-like, but not gilled) top of the stem is also very typical for erebia.

I don’t know
By: Britney Ramsey (Riverdweller)
2012-04-16 17:31:34 CDT (-0400)

which Agrocybe this is.
It matches well with the obs. Deb referenced.

the gills…
By: Richard and Danielle Kneal (bloodworm)
2012-04-16 16:33:00 CDT (-0400)

are not running down the stipe as suggested by Kuo pertaining to Agrocybe erebia.

Psath Stipes
By: Christian (Christian Schwarz)
2012-04-16 16:01:26 CDT (-0400)

Well, you can really only say the stipe is too beefy for a Psathyrella if you’ve flown forward into the cladistic-nomenclature future where things like Psathyrella spadicea have been split out from the rest of the genus.

I think a better character to focus on here is the real membranous veil. Even the velarly-well-endowed P. longistriata has a more ephemeral veil than this.

By: Richard and Danielle Kneal (bloodworm)
2012-04-16 15:35:16 CDT (-0400)

is too beefy for Psathyrella.

certainly not a Psath…
By: Debbie Viess (amanitarita)
2012-04-16 15:34:52 CDT (-0400)

waaay too robust of a stipe.

Frankly, I think that Agrocybe erebia is a pretty good fit, down to the peronate
partial veil! Check out this detailed sighting with microscopy here on MO:


Corrections welcome
By: Britney Ramsey (Riverdweller)
2012-04-16 15:25:59 CDT (-0400)

I’m struggling to understand the different cell structures I’m seeing. I believe I have everything labeled correctly in the micrographs, but the context and pileus cellular structures, I’m not confident I understand.

Also, hygrophanus
By: Britney Ramsey (Riverdweller)
2012-04-16 11:10:30 CDT (-0400)

I should have listed my notes already. I will get them listed.

Brown spores
By: Britney Ramsey (Riverdweller)
2012-04-16 11:08:35 CDT (-0400)

This left chocolate spore print on the paper towel it was wrapped in. I plan to look at this under the scope this morning.

Created: 2012-04-16 10:46:03 CDT (-0400)
Last modified: 2012-04-18 20:29:33 CDT (-0400)
Viewed: 384 times, last viewed: 2017-06-12 22:58:51 CDT (-0400)
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