Amanita muscaria — The fly agaric

Card image cap

Fly agaric from Vancouver, BC, photograph by Paul Kroeger.

Lawnmower's mushroom

Fly agaric cross-section. Gills are edged with powdery fringes; flesh just below cap is red, photograph by Paul Kroeger.

Lawnmower's mushroom

Fly agarics8, photograph by Sophie Vidal.

Lawnmower's mushroom

Fly agarics9, photograph by Ludovic Le Renard.

The fly agaric is one of the most conspicuous and showy mushrooms--the classic toadstool. Fly agarics grow from the ground near both conifers and broadleaved trees and may be common and widespread in the late summer and autumn. Cap colour of these large and stout mushrooms is typically red but varies from almost white through yellow to orange or even brown.

Odour: Not distinctive.
Cap: 5–20 (–25) cm in diameter, rounded when young and then expanding to become convex to almost flat. The colour ranges from pale yellow to brown but is often bright red or scarlet when young, fading towards the margin to orange or yellowish. The surface is smooth and can be a bit viscid when wet. The margin becomes distinctly radially grooved. The cap has scattered to dense pyramidal warts of whitish, cream or slightly yellowish veil material, aptly described as looking like “cottage cheese”. These warts wipe off easily by hand or with rain. The flesh is white and does not stain when cut or bruised.
Gills: White and crowded and free or narrowly attached to the stem. The edges of the gills often have a powdery or granular fringe.
Stem: 7–20 cm tall and 1.5–4 cm wide, tapering towards the top, with an expanded or bulbous base, white in colour.
Ring or veil: A large, well-developed ring connects the young cap's margin to the stem. As the cap expands, the ring is released from the cap's margin and hangs like a skirt from the stem, smooth on its upper side and often with a thick cream to yellowish edge.
Cup (volva): The cup is thick and leaves broken horizontal or diagonal bands and ridges of loose, cottony, white to yellowish-cream material on the lower stem.
Spores: 9–13 x 6.5–8.5 μm, broadly ellipsoid to elongate, smooth, thin-walled and hyaline, non-amyloid (not blue in Melzer's iodine solution).
Habitat: Growing from the ground, common in cities under broad-leaved trees including oaks (Quercus spp.) and birches (Betula spp.) but also in coniferous and mixed forests; ectomycorrhizal.
Geographical range1: The fly agaric is in fact a species complex4. It is widely distributed across the Northern Hemisphere. In the Southern Hemisphere, it has been introduced with its host trees5,6. The geographical distributions of the individual component species within the fly agaric species complex are still unclear.

The rare brown-capped form of the fly agaric resembles the western panther amanita Amanita pantherinoides and the yellow-capped form resembles the gemmed amanita, Amanita gemmata. However, the fly agaric's universal veil breaks up into a series of horizontal or diagonal, loose cottony yellowish-white bands ascending some way up its stem. In contrast, the western panther's and gemmed amanita's universal veil forms a cup that frequently has a rim or collar at its top. In the western panther, the cup's rim folds outward from the stem, and in the gemmed amanita, the cup is soft and may fragment into soft patches above the basal bulb of the stem7.

The several colour forms of the fly agaric had been named formally as varieties but molecular data unfortunately did not support neat classification by colour characteristics. Instead, our western North American fly agarics represent at least three different species that do not correlate to colour forms or the named varieties.

Poisonous, contains neurotoxins causing inebriation and delirium. It has been associated with poisoning in dogs and cats as well as humans8. Some people have eaten it intentionally seeking its inebriating effects. It should be noted that very few people who have experimented with eating fly agarics have chosen to repeat the experience.

Toxins: Isoxazole compounds called ibotenic acid, muscimol, and muscazone. Small amounts of muscarine may also be present.

Symptoms8,9: Time of onset 30 min – 2 hours after ingestion. Common symptoms include disorientation, muscle spasms, disturbances in vision or perception of sound or of time, and gastrointestinal distress, often followed by drowsiness and a deep sleep lasting several hours. Recovery is usually complete after 24 hours.

Treatment: Contact your regional Poison Control Centre if you or someone you know is ill after eating any Amanita species. Poison centres provide free, expert medical advice 24 hours a day, seven days a week. If possible, save the mushrooms or some of the leftover food containing the mushrooms to help confirm identification.

Poison Control:
British Columbia: 604-682-5050 or 1-800-567-8911.
United States (WA, OR, ID): 1-800-222-1222.

MyCoPortal. Mycology Collections Portal, <> accessed March 2018.

Siegel, N. & Schwarz, C. Mushrooms of the Redwood Coast. A Comprehensive Guide to the Fungi of Coastal Northern California. Ten Speed Press, Berkeley, California (2016).

Tulloss, R. Amanita muscaria, <> accessed May 13, 2017.

Geml, J., Tulloss, R. E., Laursen, G. A., Sazanova, N. A. & Taylor, D. L. Evidence for strong inter- and intracontinental phylogeographic structure in Amanita muscaria, a wind-dispersed ectomycorrhizal basidiomycete. Mol. Phylogen. Evol. 48, 694-701, doi:10.1016/j.ympev.2008.04.029 (2008).

Bagley, S. J. & Orlovich, D. A. Genet size and distribution of Amanita muscaria in a suburban park, Dunedin, New Zealand. N. Z. J. Bot. 42, 939-947, doi:10.1080/0028825X.2004.9512940 (2004).

Vellinga, E. C., Wolfe, B. E. & Pringle, A. Global patterns of ectomycorrhizal introductions. New Phytol. 181, 960-973, doi:10.1111/j.1469-8137.2008.02728.x (2009).

Tulloss, R. & Possiel, L. Amanita phalloides, < phalloides> accessed May 10, 2017.

Beug, M. W., Shaw, M. & Cochran, K. W. Thirty-plus years of mushroom poisoning: Summary of the approximately 2,000 reports in the NAMA case registry. McIlvainea 16, 47-68 (2006).

Michelot, D. & Melendez-Howell, L. M. Amanita muscaria: chemistry, biology, toxicology, and ethnomycology. Mycol. Res. 107, 131-146, doi: (2003).

Specimen Amanita muscaria UBC F33057, GenBank #MF908458.

Specimen Amanita muscaria UBC F32051, GenBank #MF954663.