amanita muscaria var. guessowii mushroom

Yes, this Yellow Amanita is Psychoactive—But It’s Not Like A Magic Mushroom

And this mushroom is easier to mistake for deadly look-alikes

DoubleBlind Mag

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Updated December 22, 2023

Amanita muscaria var. guessowii, or the eastern yellow fly agaric as some American mycologists call it, was first described by the Canadian state botanist Hans Güssow in 1927 as Amanita muscaria after finding a yellow version of it around the city of Ottawa. Later in 1933, Czech mycologist Rudolf Veselý applied the Latin name A. muscaria var. guessowii to distinguish it from a similarly yellow variety found growing in Europe, named A. muscaria var. formosa

Now would probably be a good time to discuss varieties in the context of fly agarics. Though it’s a term thrown around a little haphazardly in the magic mushroom cultivation world, varieties have a stricter definition when it comes to studying mushrooms in their natural habitat. Those of you who’ve taken high school biology will know that species is a level of classification of living creatures that refers to a group of organisms that can make babies with each other—or seeds or spores if you’re less anthropocentrically inclined. Variety, then, is a classification that comes from botany and refers to a level below species that splits up this larger group classification based on interesting characteristics like color or the distinct geographic range it grows in. Like species, different varieties can successfully co-mingle their DNA, but if they’re geographically separated, they might never come into contact with each other.  

Although the eastern yellow fly agaric is found across the Northeastern forests of the United States, some mycologists argue that a geographically separate group of yellow fly agarics found growing in the Pacific Northwest are, in fact, the formosa variety. However, it needs to be clarified how the American formosa variety is related to the aforementioned European variety, with some arguing that the two shouldn’t share a Latin name. 

Safety Note

Muscimol is NOT psilocybin. Muscimol is a powerful and often dangerous deliriant that can place consumers into a coma-like sleep in high doses. It can cause dissociation, agitation, and a loss of rational thought, inspiring people to act in ways that otherwise might not. Hallucinogenic Fly Agaric mushrooms increase the risk that someone may pose harm to themselves. It is not recommended to take this mushroom in high doses. Nor is it recommended to take this mushroom alone. Find the US poison control hotline here: 1-800-222-1222

Amanita muscaria var. guessowii mushroom
Photo by Jimmie Veitch

A. muscaria var. guessowii Potency

Unlike the magic mushrooms that most associate with psilocybin, psilocin, and a host of other alkaloids, fly agarics contain a completely different chemical kaleidoscope of compounds that act on entirely different areas of our nervous system. The main compounds responsible for a fly agaric trip are ibotenic acid and muscimol. Though the effects of ibotenic acid specifically are hard to study in isolation, these two compounds that are thought to be mostly responsible the fly agaric trip—including both positive feelings like euphoria, synaesthesia, and dreamlike states, as well as adverse effects like nausea and muscle twitching. 

The fly agarics contain a completely different chemical kaleidoscope of compounds that act on entirely different areas of our nervous system.

Ibotenic acid was named after the Japanese word for the warted Amanita—ibotengutake (疣天狗茸), which roughly translates to “warty spirit mushroom”—and is broken down into muscimol via a process known as decarboxylation, which can be achieved through drying with heat, or sometimes boiling in an acidic solution. This decarboxylation also happens inside the body. However, ingesting raw fly agaric may have more negative side effects, so most prefer to dry or boil their mushrooms to avoid this. 

Amanita muscaria var. guessowii mushroom
Photo by Eva Skific

Most potency studies have been carried out on the Euro-Asian fly agaric (Amanita muscaria var. muscaria) and the panther cap (Amanita pantherina), with the potency of other species and varieties remaining mostly unresearched. Based on existing studies and anecdotal evidence, the potency of fly agaric and its varieties can vary wildly between individual mushrooms, as well as batches of mushrooms collected in different places or at different times of the growing season. Fly agaric also shows differences in potency across different parts of the same mushroom, with the caps being the strongest, followed by the bulb at the base of the stem, and finally, the stem itself. The effects of fly agaric’s compounds can be felt after consuming approximately six milligrams of muscimol, or 30 to 60 milligrams of ibotenic acid. Some studies have estimated that wild-growing A. muscaria can contain between 0.004-0.12 percent muscimol and 0.018-0.2 percent ibotenic acid, depending on which part of the mushroom was analyzed. Based on the muscimol measurements from this study alone, an active dose could be anywhere between 50 milligrams and 1.5 grams of dried fly agaric mushrooms—a difference of 30 times between the most potent and weakest mushrooms! For the eastern yellow fly agaric specifically, Kevin Feeney, PhD, lists this variety as “mildly to moderately psychoactive” and considers a low dose to be anywhere between 5-15 dried grams.

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Due to these large differences in potency, some authors recommend blending batches of multiple dried mushrooms together to even out the differences, then dose cautiously at first to understand the potency of the prepared batch. However, due to the high chance of misidentification among the fly agarics, it’s important to be confident that every single mushroom in the batch is not a deadly species picked up by mistake! 

READ: The Trippy Truth About Amanita muscaria, The World’s Most Famous Mushroom

Amanita muscaria var. guessowii mushroom
Photo by Walt Sturgeon

Safety Note

It’s recommended to have a sitter, shelter, and a warm safe place to stay when working with this mushroom and hallucinogenic doses of amanita. Fly Agaric mushrooms can cause consumers to fall into a stupor, as well as a a state of agitated delrium, particularly at high doses. Users risk accidental injury and harm. Learn more about the Fly Agaric mushrooms here.

A. var. guessowii Habitat 

The yellow eastern fly agaric has been found growing all across the Northeastern forests of the United States, as far south as Tennessee and as far north as Minnesota. This mushroom has also been found growing across the border into Québec province of Canada. 

A. var. guessowii Growing Conditions 

Many Amanita species, including A. muscaria var. guessowii are ectomycorrhizal, meaning that their mycelium form symbiotic relationships with trees and other plants—wrapping around their roots and trading water, nitrogen and fungally-released minerals for tasty carbohydrates made through the host plant’s photosynthetic processes.

In the case of the eastern yellow fly agaric, some mycologists report that it is usually found in association with conifers such as pine (Pinus), spruce (Picea), fir (Abies) and larch (Larix), though others have also reported it growing alongside hardwoods like aspen (Populus), beech (Fagus), birch (Betula) and oak (Quercus). Your best chance of finding the eastern yellow fly agaric is through summer and fall, especially after heavy rains.

READ: How To Identify Magic Mushrooms: A Step-By-Step Guide

Guessowii Identification 

The eastern yellow fly agaric can be found growing singly or in small groups of individual mushrooms. Like all Amanita species, the mushroom starts its growth by “hatching” from an egg-like sac called a universal veil. As the mushroom grows, this veil breaks leaving concentric scaly rings at the bulbous base of the stem—a feature that is often used to tell it apart from similar species. 

The eastern yellow fly agaric grows up to six inches (15 cm) tall, with a cap that can reach seven inches (18 cm) in diameter. As the common name of this mushroom suggests, the cap is a bright yellow color, though it can sometimes take on a slightly orange hue. Characteristically, the cream or pale tan colored flecks on the cap of fly agaric are remnants of the universal veil, though they can be washed away by heavy rain which can cause difficulty in identification. As the mushroom matures, lines (striations) can become more visible at the edge of the cap. The white to pale cream gills are crowded under the cap, and narrowly attached (adnate), or sometimes free from the stem.

The stem itself has a bulbous base that narrows upwards before slightly flaring out where it joins the cap. A membrane called a partial veil is attached to the stem under the cap, which covers the gills in younger mushrooms and loosely hangs down from the upper stem in older specimens. Above this veil, the stem is powdery, and below it, the stem is covered in fine fibers that become more shaggy and scaly towards the base.

Guessowii Spore Print 

Like all mushrooms in the genus Amanita, the eastern yellow fly agaric has a white spore print.

A. muscaria var. guessowii Look-alikes 

A. muscaria is currently thought to be what biologists call a “species complex”—this means that the current Latin name is likely a catch-all for a number of distinct species with similarities in their appearance. Studies have found that differences in cap and wart color across the species complex can sometimes overlap, making precise identification difficult without genetic sequencing.  

Amanita muscaria var. guessowi mushroom lookalikes
From Top Left: Amanita crenulata by Eric Smith, Amanita flavoconia by Eric, Amanita frostiana by Samantha Petrarca; From Bottom Left: : Amanita gemmata by Alan Rockefeller, Amanita persicina by Jimmy Craine, Amanita praecox by Eva Skific, Amanita wellsii by Sam Willis

The wider Amanita genus contains a range of different species: from the tasty to the intoxicating to the outright deadly. As a result, many experienced mycologists recommend beginners avoid consuming any of this genus of mushrooms unless they are 100 percent certain of which species they’ve gathered. Adding to these cautionary words, Kevin Feeney, who wrote “Fly Agaric: A Compendium of History, Pharmacology, Mythology, & Exploration” in 2021, states that “of all the fly agaric varieties guessowii shares its range with the highest number of look-alikes.” These look-alikes include:

  • Amanita crenulatatypically smaller and less brightly colored. This species lacks the concentric scaly rings at the base of the stem, which are typical of the eastern yellow fly agaric and other Amanita muscaria varieties. 
  • Amanita flavoconia: typically smaller and has a base lacking concentric scaly rings. This species is also known as the yellow dust Amanita due to the dusty appearance of the stem.
  • Amanita frostiana: the cap of this mushroom has a color, but the warty remnants of the universal veil are more yellow than off-white.
  • Amanita gemmata: similarly yellow colored, but with a more pronounced collar around the base of the stem.
  • Amanita persicina: very similar looking, but found more towards the southern end of the eastern yellow fly agaric’s range. The cap of this species is more of a peach-orange color.
  • Amanita praecox: a much smaller mushroom. The cap of this species is a paler, dull yellow, and its warts are less firmly attached, often being washed away completely by rain.
  • Amanita wellsii: typically smaller and has a base lacking concentric scaly rings. It has a yellowish stem, and the cap may have woolly fragments attached to its edge.

Though these look-alikes might confuse the experienced mushroom hunter, amateurs can easily mistake more deadly Amanita species. Though most deadly Amanitas tend to be white, the cautiously-named death cap (Amanita phalloides) has a yellowish tone that some could mistake for the eastern yellow fly agaric.

Guessowii is sometimes mistaken for edible Amanita basii (sometimes just called amarillo, “yellow” in English), a popular choice among foragers in Mexico. Basii grows natively in Mexican pine forests but does not grow in the same northern climates as guessowii. Perhaps needless to say, the psychoactive effects of guessowii can surprise someone who thinks they have basii. It’s important for non-Spanish speakers to know that amarillo describes not only color but is a common name for a particular mushroom species.

Equally, Guessowii and other North American amanitas look similar to edible mushrooms that grow in Burma, China, and other parts of the world as well. In 2018 the Center for Disease Control reported at least one Karen man picked and consumed the eastern fly agaric as it resembled the edible ochre mushroom (Amanita hemibapha), which is found growing across Southeast Asia. In 2006, nine members of an extended Hmong family all inadvertently consumed the deadly eastern destroying angel (Amanita bisporigera). Six of the family were hospitalized, and one ten-year-old girl sadly died of organ failure. 

If you’re used to foraging for amanita mushrooms in your home country, it’s important to check for poisonous local look-alikes if you’re foraging for guessowii in the United States. Accidentally mistaking amanitas here for a mushroom native to other parts of the world can have dangerous consequences. 


Consume at your own risk. Amanita mushrooms are—in many ways—more dangerous than psilocybin mushrooms. Never eat them alone, and always consume with the utmost caution. This article is intended for educational purposes and should not be used in place of medical advice. DoubleBlind does not advocate participating in illicit activities. Always consult your local drug laws before engaging with any unregulated substance.

In the event of an emergency, please dial local emergency services. For substance abuse help in the U.S., please dial the Substance Abuse and Mental Health Services Administration National Helpline at +1 (800) 662-4357.

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DoubleBlind is a trusted resource for news, evidence-based education, and reporting on psychedelics. We work with leading medical professionals, scientific researchers, journalists, mycologists, indigenous stewards, and cultural pioneers. Read about our editorial policy and fact-checking process here.

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DoubleBlind Magazine does not encourage or condone any illegal activities, including but not limited to the use of illegal substances. We do not provide mental health, clinical, or medical services. We are not a substitute for medical, psychological, or psychiatric diagnosis, treatment, or advice. If you are in a crisis or if you or any other person may be in danger or experiencing a mental health emergency, immediately call 911 or your local emergency resources. If you are considering suicide, please call 988 to connect with the National Suicide Prevention Lifeline.

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