#069: Amanita muscaria, Part 1: The Type Mushroom [Archived]

Note: This is an archived post. You can find the current version of this post here.

You are undoubtedly familiar with this mushroom, even if you recognize neither its scientific name, Amanita muscaria, nor its common name, “The Fly Agaric.” If the word “mushroom” does not immediately bring this fungus to mind, then the word “toadstool” probably does.  You have certainly encountered Amanita muscaria’s distinctive red cap with white spots in a wide variety of visual art forms.  This toadstool frequently pops up in paintings, cartoons, video games, movies, and decorations.  It is because of the artistic over-use of the Fly Agaric that I referred to it above as “The Type Mushroom.”   When describing a new taxonomic division or species of fungi, mycologists collect a “type specimen” which best exemplifies the characteristics of that taxon.  This ensures that future mycologists know exactly what the original author intended to include in that taxon.  In human society, muscaria has become the type specimen for mushrooms.  This is probably best illustrated by the Wikipedia page for “Mushroom,” which features a prominent picture of the photogenic Fly Agaric.

Amanita muscaria produces large, umbrella-shaped mushrooms with a circular, brightly-colored pileus and a central, white stipe.  Although artists usually depict the Fly Agaric with a red cap, the color of the pileus varies from red to orange to yellow to white.  When fresh, the pileus is adorned with pale, cottony bumps known as warts.  The warts are also variable in color: they may be white, off-white, or even yellowish.  Warts are remnants of the universal veil, an external membrane that protects the developing mushroom.  Immature Fly Agaric mushrooms still enclosed by the universal veil are white, egg-shaped, and known as “buttons.”  As the mushroom matures, the expanding pileus breaks through the universal veil.  There are a number of ways that the universal veil can fragment, but in the Fly Agaric it always breaks up into small, evenly spaced, bumpy warts.  The warts can be easily brushed off of the cap, so they are sometimes not present on older specimens.  At first the pileus is roughly spherical in shape, but it soon opens up to become convex.  Older mushrooms may have a pileus that is mostly flat.  The pileus ranges in size from 5cm (3in) in the smallest specimens to 25cm or more (about 1 foot) in the largest individuals.  Underneath the pileus, A. muscaria forms white gills that are close together.  These plates of tissue are perpendicular to the cap surface and radiate out from the central pileus.  The gills produce basidiospores (sexual spores) and are designed to greatly increase the surface area on which spores are produced.  Like other Amanita species, the gills are not attached to the stipe and give a white spore print.  The white stipe, which holds the pileus and gills above the ground, is more or less equal in thickness but has a swollen base.  In the largest mushrooms, the stipe can get up to 30cm (1 foot), but in small mushrooms it may only be 5cm (3in).  Its texture is variable and can be smooth to shaggy.  The most striking feature of the stipe is its skirtlike ring.  A ring is formed when the partial veil, a membrane which protects the developing gills, separates from the edges of the pileus but remains attached to the stipe.  In the Fly Agaric, the thick, white, circular membrane drapes down from its point of attachment near the top of the stipe much like a skirt would.  One of the most important identifying features of A. muscaria is found on top of the enlarged base.  The base always has concentric rings of tissue around the top edges.  These rings are the remains of the lower half of the universal veil (the top half resulted in warts on the pileus).  In most other Amanita species, the lower universal veil remains are sac-like and do not form concentric rings.

Amanita muscaria is found on the ground in mixed forests throughout the northern hemisphere, where it forms mycorrhizal associations with both conifers and hardwoods.  These relationships are mutualistic, where the tree gives the fungus sugars and the fungus gives the tree hard-to-get nutrients like phosphorous.  As a result of these associations, A. muscaria is often found fruiting in fairy rings around its host tree.  Although the Fly Agaric can form mycorrhizae with a wide variety of tree species, its preferred hosts vary by geographical region.  Partner preference is not the only characteristic that varies by region: cap color and size easily differentiate a number of varieties or subspecies of A. muscaria.  Mycologists denote these differences by adding “var. _____” to the end of the scientific name.  We seem to have at least four varieties in North America.  The red variety (var. flavivolvata) is usually found in the Deep South and in the West.  In the East, the most common cap color is yellow (var. percisina).  An orange variety (var. guessowii) can be found in the Midwest and East.  The white variety is less common but can be found throughout the continent.  However, recent genetic evidence suggests that different cap colors do not necessarily indicate different genetic relationships.  Because subspecies of A. muscaria are currently defined by color and geographical region, genetics may soon redefine these straightforward divisions.

You may have heard of people eating the Fly Agaric for its hallucinogenic effects, but this is risky.  Although A. muscaria does contain mind-altering compounds, it also contains gastrointestinal irritants.  Because of the great variety within the species, it is impossible to say which of these affects will be stronger in a specific mushroom.  There are a number of methods which supposedly reduce the poisonous effects of the mushroom, but these are unproven and sometimes just plain gross.  For these reasons and because other deadly Amanita species may be mistaken for the Fly Agaric, mycologists recommend against eating A. muscaria.  The psychoactive compounds in A. muscaria are ibotenic acid and muscimol.  Ibotenic acid activates NMDA receptors and muscimol activates GABA receptors.  These two compounds result in hallucinations, “expanded perception,” perceiving objects as larger than they are, and fear inhibition.  Other side effects of these compounds include a dry mouth and rapid heartbeat.  Studies of ibotenic acid and muscimol in mice have shown that they inhibit learning in the amygdala, which blocks fear and suppresses the startle reflex.  Depending on the relative abundance of these compounds, symptoms can range from mild intoxication to those of alcohol poisoning to hallucinations.  It seems to me that drinking alcohol is a much safer and more reliable way to achieve these same effects.  In some places, people found a rather unusual use for these toxins.  They would drop pieces of the mushroom into milk and leave it out for the flies to drink.  The flies would become intoxicated, crash into walls, and die.  This use of the toadstool gave it the common name “The Fly Agaric” (the term “agaric” means the mushroom has gills).

Most people are familiar with Amanita muscaria through the impacts it has on contemporary culture.  Although the Fly Agaric’s cultural presence is subtle, it is used as the typical mushroom and therefore appears in a wide variety of places.  Perhaps one of the most significant impacts is found in the Mario video games.  The character Toad, power-up mushrooms, and many elements of the scenery are based on A. muscaria.  I often refer to the Fly Agaric as “The Mario Mushroom” because that immediately calls to mind a colorful toadstool with white spots on the cap.  The mushroom can also be found in the Pokémon video games, sprouting out of the back of Paras.  A. muscaria is present in a variety of art as well.  Paintings, drawings, cartoons, and sculptures that include a mushroom usually opt for the colorful and recognizable Fly Agaric.  Artworks depicting fairies or small animals sitting on/under/beside a mushroom almost always use A. muscaria.  Lawn ornaments frequently feature small gnomes perched atop the Fly Agaric.  The toadstool also gets an occasional cameo on the silver screen.  In Fantasia, an A. muscaria fairy ring dances around to the tea dance from Tchaikovsky’s The Nutcracker.   In many European countries, the Fly Agaric is a symbol of good luck and can be found alongside (or in place of) four-leaf clovers.  A. muscaria is also a frequent addition to otherwise bland Christmas tree ornaments.  Because of its over-use, artists occasionally get the mushroom’s ecology wrong.  Most of the time, the Fly Agaric is correctly depicted growing from the ground.  Sometimes, however, artists put the mushroom in the wrong environment.  One example of this is the Pokémon games, where it is parasitizing an insect.  I have also seen paintings depicting the toadstool decomposing logs.  These instances always make me sad because there is such an amazing diversity of beautiful fungi that could be used without ignoring their proper habitat.

Amanita muscaria also had a profound impact on ancient cultures.  Unfortunately, this post is already very long, so you will have to wait until next year to read about how the Fly Agaric influenced the Vikings, Hinduism, Christianity, and others (or you can always do your own research).

See Further:

http://www.mushroomexpert.com/amanita_muscaria_flavivolvata.html

http://botit.botany.wisc.edu/toms_fungi/dec99.html

http://www.botany.hawaii.edu/faculty/wong/BOT135/Lect18.pdf?q=amanita

http://www.botany.hawaii.edu/faculty/wong/BOT135/Lect20a.htm