Amanita muscaria var. guessowii

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Amanita muscaria var. guessowii
A mature Amanita chrysoblema yellow-orange variant mushroom under a northern white pine in Ovid, Michigan, United States
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Fungi
Division: Basidiomycota
Class: Agaricomycetes
Order: Agaricales
Family: Amanitaceae
Genus: Amanita
A. c. var. yellow-orange
Trinomial name
Amanita chrysoblema var. yellow-orange
Amanita chrysoblema yellow-orange variant
View the Mycomorphbox template that generates the following list
Gills on hymenium
Cap is flat or convex
Hymenium is free
Stipe has a ring and volva
Spore print is white
Ecology is mycorrhizal
Edibility is poisonous or psychoactive

Amanita chrysoblema yellow-orange variant,[citation needed] commonly known as the American yellow fly agaric, is a basidiomycete fungus of the genus Amanita. It is one of several varieties of muscaroid fungi, all commonly known as fly agarics or fly amanitas.



The cap is 4.5–16 (18) cm wide, convex, and becomes broadly convex to flat in age. It is bright yellow or yellow-orange, usually more orange or reddish orange towards the disc, and fading to pale yellow. The volva is distributed over the cap as cream to pale tan warts; it is otherwise smooth and sticky when wet. The margin becomes slightly striate in age. The flesh is white and it does not stain when cut or injured.


The gills are free to narrowly adnate, subcrowded to crowded, cream to pale cream, truncate, unevenly distributed, of diverse lengths, and plentiful.


Amanita chrysoblema yellow-orange variant[citation needed] spores are white in deposit, broadly ellipsoid to ellipsoid (infrequently subglobose or elongate) and inamyloid. The spores are (7.0–) 8.7-12.2 (-14.8) x (5.9) 6.5–8.2 (9.5) µm.


The stipe is 1–3 cm, more or less equal or narrowing upwards and slightly flaring at the apex. It is white to yellowish cream, densely stuffed with a pith, the skirt-like ring is membranous, persistent, the lower stipe and upper bulb are decorated with partial or complete concentric rings of volval material that are bright pale yellow to cream or sordid cream.

Microscopic features[edit]

Clamps are present at bases of the basidia.

Distribution and habitat[edit]

Amanita chrysoblema yellow-orange variant[citation needed] is found growing solitary or gregariously, it is mycorrhizal with conifers mostly but also deciduous trees as well, it is found often in the fall but sometimes in the spring, common in the northeast, from eastern Canada to North Carolina, northwest Florida, and west to Michigan.[1]


As with all other muscaroid mushrooms, Amanita chrysoblema yellow-orange variant[citation needed] contains ibotenic acid, and muscimol, two psychoactive constituents which can cause effects such as hallucinations, synaesthesia, euphoria, dysphoria and retrograde amnesia. The effects of muscimol and ibotenic acid most closely resemble that of any GABAergic compound but with a dissociative effect taking place in low to mid doses which are followed by delirium and vivid hallucinations at high doses.

Ibotenic acid is mostly broken down into the body to muscimol, but what remains of the ibotenic acid is believed[2] to cause the majority of dysphoric effects of consuming A. muscaria mushrooms. Ibotenic acid is also a scientifically important neurotoxin used in lab research as a brain-lesioning agent in mice.[3][4]

As with other wild-growing mushrooms, the ratio of ibotenic acid to muscimol depends on countless external factors, including: season, age, and habitat - and percentages will naturally vary from mushroom-to-mushroom.


See also[edit]


  1. ^ "Shroomery - Hunting Fly Agarics in North America".
  2. ^ Stebelska, Katarzyna (2013). "Fungal Hallucinogens Psilocin, Ibotenic Acid, and Muscimol". Therapeutic Drug Monitoring. 35 (4): 420–442. doi:10.1097/FTD.0b013e31828741a5. PMID 23851905. S2CID 44494685. Retrieved 4 March 2023.
  3. ^ Becker, A; Grecksch, G; Bernstein, HG; Höllt, V; Bogerts, B (1999). "Social behaviour in rats lesioned with ibotenic acid in the hippocampus: quantitative and qualitative analysis". Psychopharmacology. 144 (4): 333–8. doi:10.1007/s002130051015. PMID 10435405. S2CID 25172395.
  4. ^ Isacson, O; Brundin, P; Kelly, PA; Gage, FH; Björklund, A (1984). "Functional neuronal replacement by grafted striatal neurones in the ibotenic acid-lesioned rat striatum". Nature. 311 (5985): 458–60. Bibcode:1984Natur.311..458I. doi:10.1038/311458a0. PMID 6482962. S2CID 4342937.

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