Observation 97683: Agaricus arvensis Schaeff.
When: 2012-06-18
Collection location: Altenahr, Germany [Click for map]
No herbarium specimen
0 Sequences

Agaricus. Very lage. Some specimen up to 30cm.

Proposed Names

27% (1)
Recognized by sight

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Eye3 = Observer’s choice
Eyes3 = Current consensus


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Gills greyish
By: deuteragenie
2012-06-19 12:20:01 PDT (-0700)

Gills being greyish rather than pink for young specimens. SHouldn’t it be arvenses ? But then, they were many very large specimens, so what’s wrong ?

One more pic
By: deuteragenie
2012-06-19 12:12:12 PDT (-0700)

One more pic uploaded, from profile and showing size (some specimens were even bigger !)


By: Gerhard Koller (Gerhard)
2012-06-19 11:58:21 PDT (-0700)

Now I am tending to arvensis group again. Cogwheel ring, yellow staining, rather thin stalk. Could be arvensis itself.
A. macrosporus as I know it has a stout stem as has urinascens.

Additional pics uploaded
By: deuteragenie
2012-06-19 11:56:17 PDT (-0700)

Young specimen pics uploaded.
! two days in fridge…

more photos would have helped with this ID…
By: Debbie Viess (amanitarita)
2012-06-19 11:02:53 PDT (-0700)

next time, please show the entire mushroom!

Thanks for those “best guesses” Irene.

Here’s link to A. macrosporus (A. urinascens) on Rogers Mushrooms:


Does the name “urinascens” come from the fact that w/age the mushroom smells like ammonia???

Here’s a link to an A. macrocarpus page:


In addition to having smaller spores (need a scope to tell), the mature cap edge of macrocarpus is entire, not toothed like in macrosporus.

Not many Agaricus
By: Irene Andersson (irenea)
2012-06-19 10:44:57 PDT (-0700)

are reaching that size – urinascens(macrosporus) or macrocarpus. They can be told apart by the spore size..

By: Johannes Harnisch (Johann Harnisch)
2012-06-19 10:39:54 PDT (-0700)

I am not very familiar with A. arvensis

Surely no arvensis.
By: Gerhard Koller (Gerhard)
2012-06-19 10:33:23 PDT (-0700)

But if in this group the ring should be like a cogwheel ornamentation.
It is too slender for arvensis. And the color too does not fit.

prob. not arvensis…
By: Debbie Viess (amanitarita)
2012-06-19 10:32:26 PDT (-0700)

which would be showing a lot more yellow by now, and has a fennel or almond odor.
not familiar with German Agaricus sp.; can you smell phenol?

Might be Agaricus arvensis
By: Johannes Harnisch (Johann Harnisch)
2012-06-19 10:27:01 PDT (-0700)

but what did the underside of the ring look like?
did it have patches like this http://mushroomobserver.org/image/show_image/74705?obs=32212&q=Kr3q

see also these Observations http://mushroomobserver.org/observer/index_observation?q=Kr3q

By: deuteragenie
2012-06-19 10:17:33 PDT (-0700)

Flesh discolor yellow, but only very slightly

did the flesh discolor yellow or any other color?
By: Johannes Harnisch (Johann Harnisch)
2012-06-19 09:58:14 PDT (-0700)
By: deuteragenie
2012-06-19 09:53:46 PDT (-0700)

Gills: first greyish, then salmon then dark brown for oldest specimen
Taste is good, but less strong than typical “champignon de Paris”

What color are the gills?
By: Johannes Harnisch (Johann Harnisch)
2012-06-19 08:01:17 PDT (-0700)
Do you have another photo?
By: Gerhard Koller (Gerhard)
2012-06-19 00:21:22 PDT (-0700)

More info
By: deuteragenie
2012-06-19 00:02:51 PDT (-0700)

Odor : mushroomy, but very light
Gills ivory, turning pink then dark brown
Flesh: stable, turning just a little bit yellow
Taste: not bad, but not very pronounced compared to shop sold “champignon de Paris”.

Once again, more info please!
By: Gerhard Koller (Gerhard)
2012-06-18 14:19:11 PDT (-0700)

Underside, ring, ODOR, change of color in flesh are the most important features for Agaricus.

Created: 2012-06-18 12:17:34 PDT (-0700)
Last modified: 2012-06-19 21:17:02 PDT (-0700)
Viewed: 108 times, last viewed: 2017-07-09 03:36:39 PDT (-0700)
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