Cap 7-19 cm broad, cylindrical to convex, expanding to nearly plane in age; surface dry, ground color pallid to white, covered with fine, appressed greyish-brown scales, concentrated at the disc; flesh white, thick, slowly becoming vinaceous when injured; odor strongly of phenol; yellowing in KOH.
Gills free, close, at first whitish, then pink, finally blackish-brown.
Stipe 8-15 cm long, 2-3.5 cm thick, equal to slightly enlarged at base; surface white, smooth above and below the ring; veil membranous, thick, white, upper and lower surface smooth, forming a medially positioned, persistent ring; stipe base typically yellowing when bruised and smelling of phenol.
Spores 4-6.0 x 3.5-4.5 µm, smooth, elliptical; spore print blackish-brown.
Solitary, in small groups, or cespitose clusters on disturbed ground under conifers; fruiting from early to mid-winter.
Toxic; like other phenolic-odored Agaricus species, it can cause gastrointestinal upsets.
Agaricus praeclaresquamosus is a large, strikingly beautiful mushroom which unfortunately for the mycophagist, is toxic. Its squamulose cap and stature resemble Agaricus augustus, an excellent edible, but the latter has tawny-brown not grey-brown cap scales, an anise, not phenol odor, and the flesh does not discolor vinaceous-brown. Additionally, Agaricus praeclaresquamosus fruits from mid to late winter, while A. augustus fruits usually during the late spring, summer and early fall.