More on that alleged A. campestris

Richard W. Kerrigan rwk at
Fri Aug 18 08:42:24 EST 1995

Unfortunately there has not been much critical work on Agaricus in 
northeastern North America since Peck and Murrill worked here about a 
century (!) ago.  A.H. Smith collected and observed this group but never 
prepared a monographic treatment.  Names and concepts need review; 
poorly-known species surely exist.  IMHO we can be collectively ashamed 
of how poorly known this genus is in almost all of North America.

I think the most accessible work on recognizing subgroups within the genus
may (ahem) be my own: Agaricales of California. Vol. 6. Agaricaceae. Mad
River Press, Arcata, CA. 1986.  The species treatment is Californian, but
the groupings hopefully hold for at least the temperate Northern
Hemisphere.  On request I will fax or smail-mail the 'keys to groups' to
interested parties (see my .sig at end of message).  Anyone blessed with
good, fresh material will, using odor, color changes, and macrochemical
spot-tests, usually be able to recognize one of six biochemical syndromes
and place their material within a sectional-level group. 

Phenotypes of these mushrooms can be quite variable and are subject to 
environmental modification.  This, or age differences, could explain 
variation 'along a path'.  Most evidence suggests that mycelia are quite 
individualistic; mosaics or hybrids are considered unlikely.  A possible 
exception to this in A. bisporus in nature is noted in an upcoming paper 
in Can. J. Bot.

Tryggvi Emilsson (emilsson at wrote:
: griner at (George Riner) writes:

: >Larry Caldwell pointed out that I need to specify my location.
: >I see his point, I'm a bit new to this.

: >	These were found in eastern Massachusetts.

: >I checked up on Larry's suggestion of A. placomyces, which is what I first
: >thought when I saw them, because of the gray-ish fine fibrils.

: >I picked a dozen, in various stages of maturity, and was expecting a
: >phenolic/iodine odor and some bruising.  But there was a complete lack
: >of both features.  And, the younger stages don't have quite the strong 'boxy'
: >look to the cap that I've seen (Arora uses the term 'marshmallow-shaped').

: >I'd be glad to hear from Barnaby Dillar again about his A. campestris-like
: >stuff that grows in the woods.  Any references you can point me to?

: A number of years ago I saw an interesting bunch of agaricus along a 100 meter
: segment of a path through some woods near Urbana,Illinois.On one end there
: were mushrooms that fit the textbook description of A.Placomyces,squarish
: top,strong phenolic "fragrance",gray-ish fibrils,etc. On the other end of
: the path there were mushrooms that I could not quite match exactly to anything
: in my fieldguides,but had rounder caps,lighter color and looked like A.Sylvati-
: cus (I think,- it's been a long time...). Along the middle of the path there
: were mushrooms with caracteristics of both,that changed smoothly from one type
: to the other.There were hundreds of mushrooms,so no mental interpolation was
: needed to notice how smooth and gradual the change was.
: The only speculation that I could make was that: a) the characteristics of
: the mushrooms depended smoothly on some characteristic of the soil,which 
: changed along the length of the path, or b) there was some wholesale mycelial
: miscegenation going on, and that I was looking at a continuous range of
: hybrids.  Is either of these scenarios plausible???

: T.Emilsson

: PS.  A few days ago I saw a few scattered agaricus along that same path.
: If anybody is interested, it would be easy enough to collect some.

Richard W. Kerrigan, Research Department, Sylvan Spawn Laboratory, Inc.		
               1163 Winfield Rd., Cabot, PA  16032  USA
e-mail:	rwk at      phone: 412-352-1521      fax: 412-352-4062
	"Success has a thousand parents; failure is an orphan"

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