Amanita muscaria

Amanita muscaria in Vancouver. Photo by Paul Kroeger

Poisonous, contains neurotoxins causing inebriation and delirium.

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

Fly Agarics grow from the ground near both conifers and broadleaved trees and may be common and widespread in the late summer and autumn. These are rather large and stout Amanitas, the cap is often wider than the stem is long. They occur in a variety of colour forms with almost white through yellow to orange to very dark red or even brown caps. The variety described here is typical for the red capped material found most often in coastal BC. They make white spore prints.

Caps 5 to 20 (25) cm wide, beginning as a hemispheric bump on top of the large developing ‘button’ but soon expanding to globular in shape and expanding further to be domed or convex to flattened or uplifted in age, viscid when wet and young, a bright red, scarlet when young fading toward the margin to orange or yellowish especially when rain soaked or exposed to strong sun. Cap margin is striate when young becoming strongly so in maturity, these striations being grooves corresponding to the gills separated by a raised ridge often with fine bumps, called tuberculate striate. Cap has scattered to dense warts or scales of whitish, cream or slightly yellowish veil material often very pyramidal in shape or aptly described as looking like “cottage cheese”. These warts are often densely distributed over the centre and more scattered toward the cap edge, and may be wiped or washed away. The flesh of the cap immediately beneath the surface is red then orange to yellow lower, then white. Flesh does not stain when cut or bruised.

Section of A. muscaria showing pigmentation and gill attachment. Photo by Paul Kroeger

Gills are white and crowded and free from the stem. Partial gills are many and truncate. The edges of the gills often have a powdery or granular fringe.

Stems are 5 to 18 cm tall and 1 to 3 cm wide and are upward tapered, white, with an expanded or bulbous base. There is usually a large well-developed skirt-like hanging ring or annulus on the upper stem which is smooth on the upper side and often has a thick cream to yellowish edge. The volva is thick and leaves more or less diagonally arranged broken bands and ridges of loose cottony white to yellowish-cream material adhering to the lower stem.

Microscopic: Spores are 9.4-13.0 x 6.3-8.7 microns, broadly elliptic to elongate, smooth, thin-walled and hyaline, non-amyloid (not blue in Melzers iodine solution).

The Fly Agaric is one of the most conspicuous and showy mushrooms and is familiar to most people as the classic toadstool. It is rarely consumed accidentally. It is intentionally ingested by some people seeking the inebriating effects, but unlike ingestions of the Panther Mushroom, these people rarely come to medical attention. This is probably because Fly Agarics contain lower and more consistent quantities of the isoxazole neurotoxins resulting in milder and more predictable effects. It should be noted that while quite a few people have experimented with eating Fly Agarics and Panther Mushrooms, very few people choose to use them repeatedly.

There are several colour forms found in Amanita that were previously formally recognized as named varieties:

  • Whitish caps with tan buff warts and white stem turning yellowish where handled characterized the variety alba, which is common in eastern North America but rare in the west.
  • Yellow to yellowy orange caps with yellowish to pale yellow tan warts and white stem surface becoming yellowish where handled were considered as belonging to the variety formosa. These are common in the west especially under Poplar trees and in interior pine woods.
  • Vivid red or orange-red caps with distinctly yellowish warts and yellowish volval remnants and white stem surface turning tannish where handled were referred to as variety flavivolvata.
  • Brown caps indicate the rare form of Amanita muscaria called the variety regalis. Though this mushroom resembles the Panther Mushroom the volva at the basal bulb is a series of more or less diagonal loose cottony yellowish-white bands ascending some way up the stem, rather than an abrupt single white collar or rim (see Amanita pantherinoides).

Molecular data unfortunately does not support this neat classification by colour characteristics. There appear to be at least three different lineages or clades or genotypes within our western North American Fly Agarics according to molecular studies but these do not correlate to colour forms or the named varieties.




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