On a big mushroom by Jaco Verheul

On a large mushroom, red with white dots

Fly agaric mushrooms grow mostly in deciduous forests, in close association (symbiosis) with birch, sweet chestnut, oak, beech, also occasionally with pine and spruce. They form an ectomycorrhiza, meaning that the mycelium does not penetrate the roots of the tree, but surrounds the hair roots on the outside. Characteristics[edit] The best-known appearance of the fly agaric is a dark red cap with white dots. The white dots are remnants of the overall envelope (velum universale) in which the mushroom was 'trapped' before emerging from the ground. These wash off the cap quite quickly in rainy weather. However, the colour of the cap is variable and can range from red to orange with yellow tones. The first photo in the photo gallery below gives an idea of the variation in colour in fly agaric mushrooms. The cap grows 5?15 cm wide.[2] The flesh, plates and spores are white. The spores are elliptical in shape (9-12 µm by 6-9 µm) and non-amyloid. There is usually a distinct ring on the white stalk and a (flaky) purse on the underside. Fly agaric can occur from July through late autumn, peaking around the end of August. Toxicity[edit] One possible explanation for the name fly agaric is that the red membrane on the cap is the part of the fungus that is thought to contain the substance muscarinic, from which a fly-killing agent could be made . Some have seen a connection with