This is probably the most exciting mushroom I have come across in my exploration of mycology so far.

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I say exciting… but perhaps it’s more accurately described as challenging, or dangerous, to identify. Just about every mushroom I gaze upon inspires awe and causes me to wonder… but I do admit that if I come across a mushroom which I can quickly identify, I feel less excited.

I find this mushroom a challenge to identify for a number of reasons… 1) most significantly, it has the potential to be edible or deadly, 2) the identification really comes down to true mycological analysis; uprooting, handling, dissecting, spore printing, and 3) if it is what I think it is, by sight, it’s atypical for the region I found it in. So I thought it would be valuable to write my thoughts down. My big question is whether it is of the Agaricus or Amanita genus.

Apparent features:

  • Large white mushroom
  • Wide convex cap with smooth surface
  • Gills appear crowded and free
  • Pendant ring veil

Unobserved features:

  • Stalk base shape, whether equal, bulbous or with a cupped volva
  • Bruising; colour reaction
  • Fragrance
  • True measurements
  • Spore print colour

Thanks to a selection of mushroom field guides, and given the three most prominent features; colour, cap and ring, I’m able to reduce the type down to either a Smooth Lepiota, an Abruptly-bulbous Agaricus, a Wood Mushroom, a Destroying Angel, a Citron Amanita or a Cleft-foot Amanita. Here is my deductive reasoning, stepping through each possibility.

Smooth Lepiota, Lepiota naucina of the Agaricaceae family – Matches the above, except cap is normally egg shaped or broad with a slight knob and from all the photos I’ve referenced, the perimeter of the cap fails to match. The Smooth Lepiota’s cap perimeter terminates above the gills, whereas this mushroom’s cap perimeter terminates below the gills. Also, the veil doesn’t appear to match; the Smooth Lepiota veil is described as a moveable ring, whereas this mushroom’s veil is clearly of the down-flaring pendant type, attached on the upside. Edibility of the Smooth Lepiota is considered choice, although with caution, as some people become ill after consuming the grayish variant.

Abruptly-bulbous Agaricus, Agaricus abruptibulbus of the Agaricaceae family – The gills of the Abruptly-bulbous Agaricus are known to transition from pink to white to brown. The description of the ring matches very well along with the reference photos. The cap perimeter and transition of gills matches. Only thing that does not match is the area in which these are typically found; Ontario and Quebec to North Carolina, west to Michigan. Considered an excellent edible, but spore print is considered necessary to differentiate from a poisonous Amanita.

Wood Mushroom, Agaricus silvicola of the Agaricaceae family – Very similar to the Abruptly-bulbous Agaricus. Seen distributed over North America and Europe, often solitary. This variant is known for being slightly smaller though, with a longer, thinner stalk. Edible and popular.

Destroying Angel, Amanita virosa of the Amanitaceae family – The ring strongly matches the description of this type; a non-moveable, flaring, skirt-like ring, although in all reference photos, I find the ring to exist near the cap, much higher than half way up the stalk. The Destroying Angel cap also appears to be shorter in height and flatter as opposed to convex, although I hesitate to judge caps in this way as they are known to develop into different shapes throughout their life. The clear indication of a Destroying Angel is the saclike cup or volva at the base of the stalk and the ring is often torn on the upper stalk.

Citron Amanita, Amanita citrina of the Amanitaceae family – Cap tends to be more yellowish to greenish-yellow than white and sticky when wet. The bulbous base and pendant ring are clear indicators, but again like the Destroying Angel, I find the ring to be higher on the stalk than the mushroom in question. The Citron Amanita should be avoided and is considered inedible due to the variety of colours and overlapping similarities to the deadly Death Cap.

Cleft-foot Amanita, Amanita brunnescens of the Amanitaceae family – Known for its brownish cap and sticky surface, looking very similar to all of the above. It has a bulbous base, not saclike though, and is observed with vertical splits. Pendant ring again, sits high on the stalk. Possibly poisonous.

Sifting through each species of mushroom, I’m finding that in this case, it’s coming down to a number of things I didn’t check when I snapped the photo. The least I could have done is uproot the stalk or clear the moss away so that the base was more apparent. If I were truly interested in feeding myself, I would have performed a spore print, as I believe it would have best determined exactly which mushroom it was. Abruptly-bulbous Agaricus would have been a purple-brown spore print. Wood Mushroom would have been brown. Smooth Lepiota, white. Destroying Angel, white, Citron Amanita, white. Cleft-foot Amanita, white. And in the case of a white spore print, the base of the stalk should clearly differentiate the edible from the non-edible. And if after all this you truly aren’t satisfied, place some gill flesh under a microscope to ensure the gill flesh is never divergent (as is the case with Amanita); the tissue strands should be parallel or interwoven.

Essentially, after stepping through all the details of these different mushrooms, given the fact that I will never know exactly which mushroom this is without the knowledge of what the stalk base or spore print looks like, I would wager to say that this is an Agaricus. I want to believe it’s the Abruptly-bulbous Agaricus, despite the fact that it’s not in the region the book declares it should be in. The thickness of the stalk and cap, the clear and uniform white colour, the proportions of the ring along the stalk, and the detail of the cap perimeter where the gills meet the cap edge… I simply don’t see this in the other mushrooms. If it really weren’t the Abruptly-bulbous Agaricus, I wouldn’t be surprised as there are something like 200 Agaricus species in North America…

Would I eat it? Given that expected purple-brown spore print and abrupt bulb, and perhaps if a mouse hadn’t defecated on it, sure I would.

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