How to identify American Fly Agaric

To correctly identify American Fly Agaric (Amanita muscaria var. guessowii), check each of these features in order. Misidentification is the most common cause of mushroom poisoning, so cross-reference multiple sources.

Step-by-step identification

1. 1

   Cap

   Shape, color, surface texture, and diameter.

   3-20 cm (1.2-8 inches) in diameter, convex to broadly convex or flat at maturity. Color ranges from golden yellow to orange-yellow, sometimes fading to pale yellow in age or with exposure. The surface is often sticky when moist, becoming dry. Typically covered with whitish to yellowish patches or warts, which are remnants of the universal veil and are easily removable.

2. 2

   Gills

   Attachment to stem, color, and spacing.

   Free to adnexed, crowded, white to cream-colored. Often with a serrated edge in mature specimens.

3. 3

   Stem

   Length, shape, surface, and any ring.

   5-20 cm (2-8 inches) long and 1-3 cm (0.4-1.2 inches) thick, tapering slightly upwards or cylindrical, flaring at the base to form a bulbous volva. White to yellowish, often shaggy or scaly above the ring. A persistent, membranous ring (annulus) is present, initially white but can become stained yellowish from spores falling onto it. The base of the stem has concentric rings or a collar of universal veil remnants, forming a distinct volva.

4. 4

   Flesh

   Color, texture, and bruising reaction.

   White, firm, and relatively thick. Does not change color when cut or bruised.

5. 5

   Fruiting body

   Overall growth pattern.

   Typical agaric (gilled mushroom) morphology with a cap, gills, stem, ring, and volva remnants.

6. 6

   Habitat

   Where it grows and on what substrate.

   Mycorrhizal with conifers and hardwoods, particularly birch, pine, spruce, and fir. Grows solitarily or scattered on the ground in woodlands.

Key Facts

Cap surfaces

Sticky when moist, dry, covered with whitish to yellowish warts/patches

Growth Form

Solitary or scattered

Spore Print

White

Body color

Cap: Golden yellow to orange-yellow; Gills: White to cream; Stem: White to yellowish

Odor

Indistinct

Flesh bruises

No bruising reaction

Height

5-20 cm (2-8 inches)

Cap Diameter

3-20 cm (1.2-8 inches)

Fruit body characteristics

• Gill attachment: Free to adnexed
• Stem shape: Cylindrical to tapering upwards, bulbous base
• Stem surface: Smooth to shaggy/scaly above the ring
• Ring: Present, membranous, white, persistent
• Stem cross-section: Solid

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