Community find

American yellow fly agaric

Amanita muscaria var. guessowii

Group

gilled mushroom

Spore print

White

Size

Cap diameter ranges from 5 to 15 cm; stipe length is 6 to 15 cm with a thickness of 1 to 3 cm.

Season

Typically fruits from late summer through late autumn.

Habitat

Grows in a mycorrhizal relationship with both coniferous and deciduous trees, frequently found under pines, spruces, and birches in lawns, parks, and woodlands.

Distribution

Common throughout northeastern North America and parts of the Midwest.

Key characteristics

Yellow to orange-yellow cap covered with small, pale yellow to whitish warts or patches. The stem is whitish to pale yellow with a bulbous base and a fragile ring. Gills are white and closely spaced.

Fruiting body

The cap is hemispherical when young, expanding to convex and then nearly flat. The surface is smooth and viscid when wet, decorated with remnants of the universal veil. The lamellae (gills) are free from the stipe. The stipe features a pendant, skirt-like ring and a base surrounded by concentric rings of veil tissue.

How to recognise it

Look for the bright yellow to orange cap, the presence of warts, and the scaly, bulbous base of the stem with concentric rings.

Look-alikes

Amanita flavoconia (yellow patches, lack of concentric rings at base), Amanita frostiana (smaller size, different striations on cap margin).

Ecological role

Mycorrhizal, forming a symbiotic relationship with tree roots to exchange nutrients for carbohydrates.

Notes

This variety is a North American relative of the classic red-capped Eurasian fly agaric. It has been a subject of extensive mycological study regarding its fungal genetics and distribution patterns across the continent.