Pluteus petasatus

Pileus
Cap 5-13.5 cm broad, convex to convex-umbonate, expanding to nearly plane, at maturity the disc sometimes depressed or raised; margin in youth, incurved, then decurved, finally plane; surface sticky when moist, otherwise dry, glabrous when young, often shiny, cream-colored with pale innate, brown fibrils concentrated at the disc, the latter occasionally becoming fibrillose to squamulose; in dry weather the cap sometimes squamulose overall; context white, unchanging, soft, up 1.5 cm thick, thin near margin; odor and taste of radish.

Lamellae
Gills free, crowded, broad, pallid, becoming cream to pinkish, finally salmon pink; not marginate; lamellulae up to four-seried.

Stipe
Stipe 5-9 cm long, 1-1.5 cm thick, straight, the apex and base often enlarged, fleshy, solid at maturity; surface longitudinally striate at the apex, white, elsewhere smooth to slightly wrinkled, in age brownish fibrils sometimes developing at the base; partial veil absent.

Spores
Spores 5.5-7 x 4-5 µm, broadly ellipsoid to ovoid, smooth, with granular contents; spore print salmon-pink.

Habitat
Clustered, less commonly solitary, on rotting chips, woody debris or logs; fruiting in late summer in watered areas or after the fall rains.

Edibility
Edible.

Comments
This infrequent Pluteus is unusual in its clustered fruiting habit. Also characteristic is a relatively smooth, sometimes shiny cap that is pallid at the margin and brownish at the disc. A related, more common species is Pluteus cervinus. It is distinguished by an entirely brown cap. Volvariella speciosa is a distant cousin similar in stature, cap, and spore color, which may also fruit in wood chips. It is easily told from Pluteus petasatus by the presence of a volva. Another look-alike occasionally found in wood chips is Agaricus californicus. It has a similar colored, though not nearly as shiny cap, and can be differentiated by a partial veil and at maturity, free chocolate-colored gills.