Common in North America and Europe, it is a secondary parasite, in that it attacks trees that have already been weakened from prior injury or infection by bacteria or other fungi.

The species was first described scientifically as Agaricus squarrosus in 1790 by Georg Christian Oeder, and later sanctioned under this name by Elias Magnus Fries in his 1821 Systema Mycologicum.

The partial veil that covers the young gills forms a thick, woolly ring on the upper part of the stem.

The spores are elliptic, smooth-walled, nonamyloid (not absorbing iodine when stained with Melzer's reagent), and measure 6.6–8 by 3.7–4.4 μm.

[7] Pholiota squarrosa is similar in appearance to species in the genus Armillaria, but the latter produces white spore prints.

[15] Another similar mushroom is Pholiota squarrosoides, which can be distinguished microscopically by its smaller spores, and macroscopically by the stickiness of the cap between the scales.

The fungus is a secondary parasite, in that it attacks trees that have already been weakened from prior injury or infection by bacteria or other fungi.

[21] The fruit bodies are used as a primary food source by the red squirrel Sciurus vulgaris, and have a higher protein content than the other mushrooms typically consumed by this species.

Xanthine oxidase catalyzes the crystallization of uric acid in the joints, a main cause of gouty arthritis, and inhibitors of this enzyme are being used clinically to reduce this side effect.

The natural function of these compounds may be to quench reactive oxygen species produced by plants as a defensive response to fungal infection.