Chlorophyllum molybdites

Pileus
Cap 5.0-15.0 (20) cm broad, paraboloid, to obtuse-conic when young, expanding to plano-convex, the disc slightly raised or depressed at maturity; margin shaggy from veil fragments in youth, incurved, becoming decurved, in age plane to elevated, occasionally wavy; surface of immature caps, brown, sometimes with vinaceous tints, glabrous to slightly matted-tomentose; with cap expansion the cuticle cracking, forming coarse, brown concentrically arranged, these, smaller and sparser towards the margin, background color white to buff-brown; context white, firm in youth, soft in age, sporadically carrot-orange to vinaceous when injured; odor and taste not distinctive.

Lamellae
Gills free, close, up to 1.5 cm broad, cream-colored, in age buff-brown to greyish-olive, the edges often brown; lamellulae two to three-seried, uncommon.

Stipe
Stipe 2.5-6.5 cm long, 1.0-2.0 cm thick, stuffed, slightly enlarged to sub-bulbous at the base; surface in youth, white, inconspicuously fibrillose to sparsely squamulose, bruising dull vinaceous-brown, then grey-brown, or in older material, directly grey-brown, context discoloring like the surface; partial veil membranous, white, thick, felty, forming a superior, buff to tan-colored annulus, with a double-edged, torn margin.

Spores
Spores 9.0-11.5 x 6.5-8.0 µm, elliptical to ovate in face-view, some apically truncate, strongly inequilateral in side-view with a well-developed belly, smooth, moderately thick-walled, dextrinoid, hilar appendage appendage prominent; spore print dull-olive to ochraceous.

Habitat
Scattered, gregarious, or in rings, primarily in grass, occasional in parks and gardens; fruiting during the summer months, common in the Central Valley and Southern California, rare in coastal areas.

Edibility
Toxic, causes gastrointestinal upsets; see "Comments" regarding confusion with Macrolepiota rachodes.

Comments
Chlorophyllum molybdites is a toxic look-alike of Chlorophyllum brunneum, a good edible species. The differences between these two species can be subtle, particularly when young. For that reason, those collecting for the table should use a combination of characters to make an identification. Chlorophyllum molybdites is distinguished from Chlorophyllum brunneum, by a less scaly pileus, a softer cap context at maturity, a sub-bulbous, not abruptly-bulbous stipe base, and greyish-olive gills in age. Additionally, the two species tend to be found in disimilar habitats, Chlorophyllum molybdites preferring warmer, inland locations and grass, while Chlorophyllum brunneum predominates in coastal areas, fruiting in cypress, eucalyptus duff, etc., or near compost heaps. Macrolepiota rachodes differs from Chlorophyllum brunneum in having an enlarged to clavate, but not abruptly-bulbous stipe, and for that reason is more likely to be confused with Chlorophyllum molybdites.