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Hunting Fly Agarics in North America

A guide to the mushroom, its varieties, and its look-alikes

Hunting Fly Agarics in North America
A Guide to the Mushroom and Its Look-alikes

Note: Throughout this guide, I will tend to refer to the mushroom in question as the fly agaric, rather than as Amanita muscaria. This is due to the fact that North American fly agarics are coming to be considered a distinct species from the Eurasian Amanita muscaria.

Proper identification is critical if one is picking this mushroom with the intent to consume it; in addition to our friendly fly agarics, the genus Amanita contains some deadly poisonous mushrooms such as the death cap (A phalloides) and the destroying angel (A bisporigera, A ocreata, A virosa, A verna). Fortunately for us, these deadly poisonous Amanitas are white, green or brown capped, and there are no red-capped varieties of Amanita that contains these lethal hepatotoxic (liver-destroying) amatoxins.

Still, it's always best to be safe and informed when picking mushrooms from the genus Amanita, or indeed any mushroom. For that reason, I'll detail in this article not only the key features by which you can recognize the fly agaric mushroom, but also how to distinguish it from the common look-alikes.  This guide is specific to the North American varieties and their look-alike species; there may be look-alikes on other continents which I do not address here.

Distinguishing Features of the Fly Agaric

The Cap and Warts

The most popularly recognized feature of the fly agaric is its distinctive bright and spotted cap. It can range in color from a deep crimson red to lighter shades of orange, or yellow-orange. There are even varieties of A muscaria which are white-capped (A muscaria var. alba), though these are probably best avoided to prevent mistaking them for a poisonous Amanita.

The cap is spherical or oval on very young specimens, opening out to a convex shape. With age, they become broadly convex, planar, or plano-depressed. The margin of the cap is often lined, particularly in more mature specimens. Here is a picture of a patch of Amanita muscaria with specimens exhibiting all of the possible cap shapes:

The spots or warts range from white to whitish-yellow; these are remnants of the mushroom's universal veil. On North American fly agarics, the universal veil is typically yellowish white. Here's a picture of a very young specimen almost entirely enclosed in its universal veil:

While the distinctive cap is the most popularly recognized trait of the species, being featured in fairy tale illustrations (as in Lewis Carroll's Alice in Wonderland) and in folk art, it is by no means a definitive means of identification. There are other red- or orange-capped species of Amanita with white or whitish-yellow spots.The best means of identifying the fly agaric is a careful examination of the stipe, particularly the base of the stipe.

The Stipe

The stipe, or stem of the mushroom, is marked by a characteristic pendant annulus (that is, a drooping skirt-like ring), which is a remnant of the partial veil. Younger specimens will not bear an annulus unless their partial veil has broken. Here's a picture of a specimen in which the partial veil has just begun to break (it's still attached on the right, and beginning to separate on the left):

The base of the stipe is bulbous, substantially wider than the rest of stipe, and either spherical or egg-shaped.

Just above the bulbous base of the stipe, there are concentric zones of shagginess. These fuzzy concentric rings are the most critical feature in identifying A muscaria, and one should look for this characteristic feature in every collected specimen. Here's a photo where this feature can be clearly seen:

Other Features

The spore print is white. This is not by any means a distinguishing feature, as virtually all Amanita species have a white spore print.

The gills are white, and may be attached or free from the stem. In terms of spacing, they may be either close or crowded. Again, these traits are common amongst Amanita species.

Microscopic Features

The spores are smooth, non-amyloid, and broadly ovate. They typically measure around 10 x 7 ?m. Clamps are often present at the bases of basidia.

The North American Look-alikes

In general, all three of the following species are mycorrhizal with the same sorts of trees as the fly agaric. That means that if any area looks like a perfect spot to find your fly agarics, then it's also  a perfect spot to find these look-alikes.

Also, these species all occur in eastern parts of North America. I'm not aware of any convincing look-alikes on the west coast. But that doesn't mean west coast fly agaric hunters should let their guard down. Always inspect the base of the stipe on every mushroom to confirm your finds.

Amanita crenulata
Region: Eastern North America

Considering its appearance and location, this mushroom could easily be mistaken fora pale fly agaric. One source indicates that it often groups with Amanita muscaria var. guessowii, which is a very good reason to closely inspect every mushroom in a patch of fly agarics

Key differences from the fly agaric:
  • Vovlal remnants at the base of the stipe are not organized into concentric rings, but instead presents as a single woolly ring.
  • Stipe tends to taper upward toward the cap
  • The annulus is quite fragile and may be lost as the mushroom matures.
  • Cap is often more gray-toned when young, developing yellowish tints with age

Microscopic differences:
  • Spores are more rounded, ranging from subglobose to broadly elliptical, typically measuring around 8 x 7 ?m
  • Clamps absent from bases of basidia

Amanita flavoconia
Region: Eastern North America

Key differences from the fly agaric:
  • Lacks the fuzzy concentric rings above the base of the stipe
  • Base is somewhat less swollen, and is marked by powdery yellow volva remnants
  • Stipe tends to taper more toward the cap; the stipe is generally yellowish, but may be pale enough for the color to be mistaken

Microscopic differences:
  • Spores are amyloid
  • Spores are more narrowly elliptical, typically measuring around 9 x 4 ?m

Amanita flavorubescens
Region: Eastern North America, less common but present in western North America

Key differences from the fly agaric:
  • Base of the stipe is only slightly swollen, and typically smooth
  • Cap is yellow-brown when young, typically fading to yellow with age
  • Warts vary from yellow to bright orange-yellow, stipe may be yellow or white and typically tapers toward the cap
  • Bruises shades of pink or red, most commonly in the interior of the base, but sometimes throughout the fruiting body

Microscopic differences:
  • Spores are amyloid
  • Spores are more narrowly elliptical, typically measuring around 9 x 5 ?m

Amanita frostiana
Region: Eastern North America

This species can be a very convincing look-alike for the yellow-orange varieties of A muscaria! While it's not known to contain amatoxins, the dangers of eating are not really known. This is a great reason to take great care in identification while picking.

Key differences from the fly agaric:
  • The base of the stipe doesn't bear the fuzzy concentric rings that are typical of A muscaria
  • The base of the stipe generally bears a collar around the base of the stipe, but this collar is not always present. See the first image of A frostiana above to get an idea of the appearance of the collar.
  • The cap is smaller in size than a typical cap of A muscaria, but due to morphological variability, this is not really a reliable indicator.
  • The stipe often (but not always) tapers towards the cap more significantly than in A muscaria.
  • The annulus (skirt-like ring) is fragile, and may fall off with age.

Microscopic differences:
  • Spores are globose to subglobose, typically measuring around 8.5 ?m across
  • Otherwise similar to fly agaric spores, being non-amyloid, and having clamps present at the bases of basidia

Amanita jacksonii
Region: Throughout eastern North America, from Canada to Mexico

Image Credit: Alan Cressler

This mushroom is easily distinguishable from the fly agaric, but might be mistaken by novices. It is a North American form of the European edible Caesar's mushroom (Amanita caesarea); this mushroom is a good edible, delicious when fried in butter.

Key differences from the fly agaric:
  • The flesh is distinctly yellow-hued, while fly agarics are white.
  • There are no warts upon the cap.
  • The base is encased in a white sack-like volva, as opposed to the distinctive concentric rings at the base of the fly agaric
  • The annulus occurs very near the top of the stipe.

Microscopic differences:
  • Spores are larger and more narrowly elliptical, typically measuring around 12 x 8 ?m

Amanita parcivolvata
Region: Eastern, and particularly southeastern North America

Key differences from the fly agaric:
  • Warts on the cap are somewhat less prominent
  • Lacks the distinctive concentric rings of shagginess
  • Cap tends to be bright red, while the varieties of A muscaria that occur in the same regions tend to be much more yellowish-orange.
  • Flesh tends to be substantially more yellow than A muscaria (particularly the stipe

Microscopic differences:
  • Spores are larger and more narrowly elliptical, typically measuring around 12 x 7 ?m
  • Basidia are four-spored, and basal clamps are rare

Amanita pantherina
Region: Throughout North America, Europe, and western Asia

This is not a mushroom that would be easily mistaken for a fly agaric (except perhaps Amanita muscaria var. regalis),but it deserves some degree of discussion here.  It is frequently lumped together with fly agarics when discussing their use as psychoactive mushrooms, which makes a degree of sense considering both contain ibotenic acid and muscimol. When planning this guide, consideration was given to whether it should also include information on identifying Amanita pantherina as well as fly agarics. Ultimately I decided against it for a variety of reasons.

For one thing, there's a great deal of ambiguity surrounding A. pantherina. While some people think it's more potent than fly agarics by weight, some people strongly recommend against its use, citing a much heavier load of muscarinic side-effects; others wholeheartedly encourage it as an alternative to fly agarics, citing the absence of muscarinic side-effects. It's difficult to make sense of these starkly contrasting accounts.

The biggest factor in restricting this guide to fly agarics is that I can personally endorse their use. Properly identified fly agarics consumed in appropriate dosages (with pursuant appropriate precautions) are a wonderful mushroom.  In North America, they're virtually never fatal (though there have been some near-misses when a reckless overdose is consumed as a result of misidentification, or through ignorance of their active chemicals).  A. pantherina on the other hand is associated with fatalities in North America. When this fact is combined with all the ambiguity surrounding the mushroom, I simply do not feel right including it in this guide to the fly agarics. Perhaps I malign it unfairly, and it too is safe when consumed in appropriate dosage with appropriate precautions. But this guide is a guide to mushrooms which I know to be safe when consumed properly; I don't feel comfortable discussing a similar but potentially unsafe mushroom alongside it.

Anyone thinking of consuming A. pantherinais is strongly encouraged to do their own research and draw their own conclusions. The look-alikes that are to be avoided when consuming this mushroom are different than the fly agaric look-alikes, and anyone hunting it should familiarize themselves with those look-alikes.

Key differences from the fly agaric:
  • Cap is a distinctive brown, fading with age.
  • Bears a distinct collar of volval material at the top of the basal bulb instead of concentric rings

Microscopic differences:
  • Sporesare quite similar to those of the fly agaric. They are non-amyloid,smooth, and elliptical, typically measuring around 11 x 8 ?m

The Varieties of the Fly Agaric

There are quite a number of different varieties of fly agaric out there.  All of them fit the identification guidelines outlined above, and all can be eaten for their psychoactive properties (or parboiled and cooked for their exquisite culinary properties), but there are differences between them.

The subject of nomenclature is a bit muddled at the moment, as the currently accepted system of nomenclature doesn't accurately reflect the phylogenetic relationships of the different varieties of fly agaric (phylogenetics is the study of the evolutionary inter-relatedness of different organisms). This is supposed to be rectified in the reasonably near future by Rob Tuloss renaming the muscaria group. I'll try to be as clear as possible in discussing this issues and anticipating the new nomenclature.

Currently, all varieties of fly agaric are considered to be subspecies of Amanita muscaria. However, recent phylogenetic analysis from 2006 by Geml, et al. reveals that what we currently consider to be Amanita muscariais actually composed of three separate clades (clades are separate groups of organisms which share a common ancestor in their evolutionary history). There are two Eurasian clades, one general and the other subalpine, and a North American clade.

The Eurasian clades are typified by the brightly capped subspecies currently known as Amanita muscaria var. muscaria,and are present only in Alaska and the most northwestern portions of North America (their precise range has not yet been determined). It is anticipated that the Eurasian varieties will be split into two species (subalpine and general).  The North American clade is typified by the reddish-orange subspecies currently known as Amanita muscaria var. flavivolvata. It is anticipated that all North American fly agarics (with the exception of the above-mentioned Eurasian specimens, and the PNW Yellow which I'll address later) will be renamed to Amanita flavivolvata, or a subspecies thereof.

The other significant result coming from this phylogenetic study is that cap color is actually a polymorphic trait! That means that the color of the cap is variable within a single species (for a more detailed explanation of the term, see the Wikipedia entry on polymorphism).  The study looked at both Eurasian and North American samples of A muscaria var. formosa (including var. guessowii), A muscaria var. flavivolvata, A muscaria var. alba, and A muscaria var. regalis,and discovered that all four subspecies were found both in the Eurasian and North American clades.  This indicates that these color variations are not distinct subspecies, but simply variations in form that are found throughout each species.

It should be noted that using phylogenetics as the sole factor in organizing taxonomies is not always advisable when based only on a few preliminary DNA studies. Phylogenetic trees can be subject to revision or reinterpretation with the incorporation of new data.  Also, for some of the varieties described below, phylogenetic analysis has not been able to demonstrate that they branched from their parent species at a single common ancestor. This would mean that the distinguishing features are just polymorphic traits that are biased within geographically separated populations, but are not truly distinct subspecies.

Since the renaming of the muscaria group has not yet occurred, it's useful to treat the various subspecies under the currently accepted nomenclature.

Amanita muscaria var. flavivolvata (= Amanita amerimuscaria Tuloss & Geml

Region: Western North America. From southwest Canada, down through the Sierra Nevadas and the Rocky Mountains of the desert of southwest America, and at least as far south as Andean Columbia. There may be significant gulf coast populations, with isolated occurrences as far up the Atlantic coast as Massachusetts, but it's also possible that these collections were actually A muscaria var. persicina. Consequently, the eastern limit on the region of A muscaria var. flavivolvata is currently ambiguous.

Habitat: Mychorrhizal with oaks, conifers, and a handful of deciduous trees.

Characteristic Features
  • Universal veil and warts are initially yellow; color fades with exposure to sunlight.
  • Cap is a bright red color when it first emerges, fades rapidly to red-orange, or even yellow-orange with exposure to sunlight.

This is the characteristic fly agaric of the New World, particularly in the west; eastern varieties typically have some differences in coloration(see var. guessowii and var. persicina).  All fly agaric hunters of the western coastal and mountain regions will be looking primarily for this variety.

Recently this variety was renamed as Amanita amerimuscaria.The precise relationship of this variety to the yellower eastern American varieties of the fly agaric is currently under investigation.

Amanita muscaria var. guessowii

Region: Eastern/northeastern North America.  From northeast Canada, as far south as the Appalachian mountains of North Carolina and Tennessee, and as far west as the great plains (Michigan is the furthest west point where the subspecies has been collected).

Habitat: Mycorrhizal primarily with conifers, but can also occur with some deciduous trees.

Characteristic Features
  • Volval material is cream-colored
  • The cap ranges from orange to yellow-orange, much paler than with typical var. flavivolvata, even in young specimens

This eastern North American species is often mis-named as Amanita muscaria var. formosa, and not without good reason. It is essentially a formosa-like variant of the North American clade of the muscaria group.

DNA studies have not yet shown that all guessowii are descended from a single ancestor, and its possible that the yellow cap is simply a common polymorhism in eastern fly agarics.  Therefor it's possible that the term var. guessowii will become obsolete, and the mushroom will simply be known as the yellow form of Amanita amerimuscaria. If it can be demonstrated that this variety is monophyletic (descends from a single ancestor), then it would likely be renamed to Amanita amerimuscaria var. guessowii.

Amanita muscaria var. persicina

Region: Eastern/southeastern North America.  Ranges from the gulf coast states up to New Jersey or southern New York.

Habitat: Mycorrhizal predominantly with oak and pine

Characteristic Features
  • Annulus(skirt-like ring) is white above and yellowish below. It's quite fragile, and as a result may not be seen in all specimens.
  • The characteristic fuzzy rings above the base of the stipe are weakly structured; they are often not notable in collected samples.
  • Cap is initially red-orange; with age, it takes on a peach-like color.

These eastern North American fly agarics can be easily confused with A muscaria var. guessowii. It can often require the examination of multiple specimens to be sure of the assignment.

DNAstudies have not yet shown that all persicina are descended from a single ancestor, and its possible that the peach-colored cap is simply a common polymorhism in eastern fly agarics.  Therefor it's possible that the term var. persicina will become obsolete, and the mushroom will simply be known as the peach-colored form of Amanita amerimuscaria. If it can be demonstrated that this variety is monophyletic (descends from a single ancestor), then it would likely be renamed to Amanita amerimuscaria var. persicina.

Amanita muscaria var. muscaria

Region: Europe, north Asia, and western Alaska.

Habitat: Mycorrhizal with birch, diverse conifers, and a few deciduous trees such as dwarf willow and eucalyptus.

Characteristic Features
  • Strikingly bright red cap. Does not typically fade to orange tones as A muscaria var. flavivolvata does.
  • Universal veil is white. Warts are typically white, but may take on yellowish tones.

This brightly red-capped variety is typical of the Eurasian clades of the muscaria group. It's only present in the furthest northwest reaches of North America, particularly Alaska (its precise range in North America is currently being evaluated).

Amanita muscaria var. alba 
Amanita chrysoblema 

Region: Scattered throughout North America and parts of Eurasia

Habitat: Mycorrhizal with coniferous and some deciduous trees.

Characteristic Features
  • Cap color varies from white to silvery white
  • Warts vary from white to tan
  • Possesses the characteristic shaggy concentric rings above the base of the stipe that are typical of fly agarics

The specimens of this subspecies which are found to occur sparsely throughout Eurasia belong to the Eurasian clades of the muscaria group (since this is a guide to North American fly agarics, we're not overly concerned with them.  The specimens which occur scattered through North America are a morphological variant of the North American clade of the muscaria group, and will presumably be renamed as Amanita flavivolvata var. alba. These are as edible as other fly agarics, but because of their visual similarity to lethally toxic Amanita species, it is advised that the typical mushroom hunter not pick them. The novelty of eating a white-capped fly agaric is not worth the risk of eating a deadly Amanita.

This white-capped variation seems to have arisen independently in several different regions, in both the Eurasian and the North American clades. It is clearly not monophyletic (decended from a single ancestor), and thus referring to it as a distinct subspecies is not really accurate. It's possible the term var. alba will become obsolete, and the mushroom will simply be known as the white-capped form of Amanita muscaria or Amanita amerimuscaria depending on where it occurs.

Amanita muscaria var. regalis (= Amanita muscaria var. umbrina Fr. = Amanita regalis (Fr.) Michael)

Region: Alaska and Scandinavia

Habitat: Mycorrhizal with pine and spruce, as well as birch and some other deciduous trees.

Characteristic Features
  • Cap is liver-brown in color
  • Warts vary from tan to yellow in color

In the past, this variety of fly agaric has typically been considered to be a completely separate species, Amanita regalis, but recent phylogenetic evidence has shown this assignment to be erroneous. The var. regalis specimens from Scandinavia are actually a morphological variation present in one of the Eurasian clades of the muscaria group. The Alaskan var. regalis specimens are similarly variations within the North American clade of the muscaria group (Amanita amerimuscaria).  Since it is clearly not monophyletic, the term var. regalis may become obsolete, and the mushroom would simply be known as the brown-capped form of Amanita muscaria or Amanita amerimuscaria depending on where it occurs.

Because it has traditionally been considered a separate species, I'm unaware of anyone consuming it for the psychoactive effects typical of the fly agaric, but it presumably has a similar chemical composition. To the untrained eye, it may be mistaken for an Amanita pantherina mushroom, but a careful examination of the base of the stipe should differentiate the two.

The PNW Yellow: Amanita muscaria var. unknown

Region: Pacific Northwest

Habitat: Unknown. Mycorrhizal, presumably with conifers, possibly some deciduous trees as well.

Characteristic Features
  • The skin of the cap is distinctively yellow (but still moist like other forms of A muscaria) without a trace of red or orange hue.
  • Warts and universal veil are white

This fly agaric of the pacific northwest is distinctive in that it does not belong to the North American clade of the muscaria group, unlike the other fly agarics that grow in the same region. When renamed, it will not be a subspecies of Amanita flavivolvata. At present it is not clear to me whether "PNW yellow" refers only to specimens of a strikingly pure yellow color, or whether it refers to mushrooms that are morphologically similar to the varieties currently known as var. guessowii and var. formosa.

Amanita muscaria var. formosa

Region: Eurasia (incorrectly considered to be widely distributed throughout North America by some sources; see below)

Habitat: Mycorrhizal with hardwoods and conifers.

Characteristic Features
  • Cap ranges from yellow to yellow orange
  • Differs from var. flavivolvata in that the universal veil and warts are typically white

This is the yellow-capped Eurasian variety of the fly agaric. Since it is a Eurasian variety, it's not particularly relevant to this guide, except to the extent that people erroneously apply the name to North Americanvarieties. Most commonly the name is mis-applied to A muscaria var. guessowii, to which it bears a substantial resemblance. As was mentioned earlier, var. guessowii and var. formosa are analagous in form, but occur in different clades. It's also not uncommon for A muscaria var. persicina to be referred to as var. formosa, due to the similarity between mature samples of each (but again, thesevarieties occur in different clades of the muscaria group). The term var. formosahas even been applied to the western fly agarics, though it's not clearwhether these specimens are the so-called "PNW Yellow" or just light-colored Amanita muscaria var. flavivolvata (=Amanita amerimuscaria).

In fact, the term var. formosais really an ambiguous term that is rapidly becoming obsolete, since it refers to a polymorphic form.  Since it has arisen several times independently among Amanita muscaria populations, it is not monophyletic and it's therefor improper to refer to it as an explicit subspecies. It will likely come to be known as the yellow-capped formof Amanita muscaria.

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