Monday, October 5, 2015

Native Species Profile - American Fly Agaric Mushroom (yellow variant)

Recently I have written profiles of two species of edible mushroom: the Bear's Head Tooth (Hieracium americanum) and Coral Tooth (H. coralloides).  Although many species of fungi are edible, many others are toxic.  Unless you are an expert, it is never a good idea to eat any mushroom that you find in the woods. There are many look-alike species, with some being edible and some toxic.  Even if if you see it being eaten by animal, that does not mean that it is safe for human consumption. 

One fungus that fits into the toxic category is the yellow variant of the American Fly Agaric Mushroom (Amanita muscaria var guessowii).  This species is found in deciduous and coniferous woodlands.  It's mycelium (root-like structures) are found in the ground and have a symbiotic mycorrhizal relationship with the roots of trees.  This means that the mycelium form a coating around the hair roots of trees and help the trees absorb water and minerals.  In exchange, the fungi receive sugars from the trees roots.

This variant of the American Fly Agaric has a yellow to orange cap with pinkish, tan, or white "warts" on the top.  These warts have a cottony or felt-like appearance.  The underside of the cap has white gills.  This mushroom emerges from the ground as a "button" or "egg".  To the inexperienced mushroom hunter it may appear to be a puffball.  This mistaken identity has probably resulted in many cases of poisoning.

Egg or button phase of Amanita muscaria var. guessowii
Egg or button phase of Amanita muscaria var. guessowii - this one was bright yellow

Eventually the outside edge of the cap spreads out to a width of up to 9 inches.  This cap rests atop white stalk with a bulbous base.  There is a fragile skirt-like ring part of the way up the stalk.

American Fly Agaric (yellow variant) - note bulbous base, white gills, and warts
This species is found much of eastern North America and is particularly common in the Great Lakes region.  Because this species is associated with the roots of trees, Fly Agaric mushrooms are often found in large groups and sometimes form arcs or "fairy rings".  It is most commonly seen in late summer and fall.

Amanita muscaria var guessowii - note the cottony warts

Part of a large colony of yellow American Fly Agaric

Basic Information


American Fly Agaric (Yellow variant)
Amanita muscaria var. guessowii

Size:  up to 9" wide by 12"tall
Habitat:  found on the ground under evergreen and deciduous trees
Color:  yellow to orange cap with pinkish, tan, or white "cottony" warts; white gills; white stalk
Bloom Time:  late-summer to fall


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