Cap 6-39 cm broad, rounded at first, then plane in age, surface viscid when moist; margin striate often with adhering partial veil fragments when young; cap red, usually with white warts but in one variety, yellow warts.
Gills adnexed to free, white to cream, edges roughened.
Stipe white, 7-16 cm long, 2-3 cm thick, tapering to a bulbous base; partial veil membranous, breaking to form a superior skirt-like veil. Volva consisting of two to three concentric rings at the stipe base.
Spores 9-13 x 6.5-9.5 µm elliptical, smooth, nonamyloid. Spore print white.
In the Bay Area, Amanita muscaria occurs under pines, especially Monterey and Bishop pine. Fruitings occur in early winter, and can be spectacular, with large groups or rings brightening the woods. The Fly Agaric shares the pine habitat with the much sought after King Bolete, Boletus edulis. Some mushroom hunters thus use Amanita muscaria as an indicator species.
Toxic when raw. Contains ibotenic acid and muscimol.
With its bright red, sometimes dinner plate-sized caps, Amanita muscaria is one of the most striking of all mushrooms. The white warts that adorn the cap, white gills, well developed ring and distinctive volva of concentric rings separate the Fly Agaric from all other red mushrooms. There are several color varieties of A. muscaria in the U.S. ranging from red to orange, yellow and white, but only two occur commonly in the Bay Area, Amanita muscaria var. muscaria with a red cap and white warts, and A. muscaria var. flavivolvata, with a red cap and yellowish warts. Photo at top is variety flavivolvata.