gills on hymenium

cap is flat

hymenium is free

stipe has a ring

spore print is brown

ecology is saprophytic

edibility: unknown

Agaricus moelleri (also known as the inky mushroom) is a mushroom of the genus Agaricus. It has a slender white stem which is club-shaped at its base. The stipe has a drooping ring which stains yellow very easily when bruised - this colour then changes to brown over time. The stipe flesh bruises yellow only faintly (more obvuous in the base). The gills are crowded, as is typical for an Agaricus, and are pink on young specimens, but brown to black on older specimens. The cap has a greyish-brown patch in the centre and cold grey-brown scaling on an off-white background surrounding this. The cap flesh is white and does not change colour on cutting.

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Retrieved from http://en.wikipedia.org/wiki/Agaricus_moelleri

(Basidiomycetes > Agaricales > Agaricaceae > Agaricus . . . ]

Taxonomy in Transition: ... > Agaricales > Lepiotoid Clade (J&V, 1998)

by Michael Kuo

This woodland species of Agaricus is found east of the Rocky Mountains, and appears to have a somewhat northern distribution. The flesh in the base of the stem is yellow, and the cap is covered with brownish fibers and scales, at least over the center. It is virtually identical to Agaricus praeclaresquamosus (see the right-hand column), a slightly larger species which grows in the west--and it is quite similar to Agaricus pocillator, a slightly smaller eastern species with a southerly range (see the comments below for help separating Agaricus placomyces from Agaricus pocillator).

According to most accounts, Agaricus placomyces develops brownish to yellowish droplets on the underside of its partial veil, which can be seen when the veil is still covering the gills. The droplets may be absent, however, or they may have dried out. In the latter case the result is frequently a discolored veil, the brownish droplets having created brownish stains. In the second and third illustrations to the right these stains can be seen; compare to the clean veil of Agaricus pocillator in the top illustration on the page for that species.

Agaricus placomyces is poisonous to some people; like most yellow staining species of Agaricus, it should be avoided.

Description:

Ecology: Saprobic; growing scattered or gregariously under hardwoods and in mixed woods; summer and fall; east of the Rocky Mountains, northern in distribution.

Cap: 5-12 cm, convex to broadly convex or nearly flat in age; dry; covered with brownish fibers and scales, especially over the center; whitish underneath, or pinkish in wet weather.

Gills: Free from the stem; crowded; pale grayish pink, eventually brown.

Stem: 6-15 cm long; 1-1.5 cm. thick; more or less equal, or with an enlarged base (but not typically ending in a small bulb like Agaricus pocillator); fairly smooth; white; bruising yellow, especially at the base; with a persistent ring; the partial veil when still covering the gills developing brownish to yellowish droplets.

Flesh: White throughout, staining bright yellow in the base.

Taste: Not distinctive or somewhat unpleasant; odor usually unpleasant (phenolic), but sometimes not distinctive.

Spore Print: Brown.

Chemical Reactions: Cap yellow with KOH.

Microscopic Features: Spores 5-7 x 3.5-5 µ; broadly elliptical; smooth.

REFERENCES: Peck. (Smith, Smith & Weber, 1979; Arora, 1986; Phillips, 1991/2005; Lincoff, 1992; Wood & Stevens, 2002.) Herb. Kuo 07200201, 07230303.

Agaricus meleagris is a former name--or perhaps a legitimate name for a similar species with a stronger phenolic odor, or perhaps a former name or synonym for Agaricus praeclaresquamosus. Some authors suggest that Agaricus placomyces, Agaricus praeclaresquamosus, Agaricus meleagris, and Agaricus pocillator represent a species cluster that has not yet been adequately explored and documented.

Several authors emphasize the width of the spores when separating Agaricus pocillator from Agaricus placomyces (the latter having broadly elliptical spores measuring 5-7 x 3.5-5 µ; the former with skinnier, elliptical spores measuring 4.5-6 x 3-4 µ). This seems unnecessarily arcane to me--and, more importantly, potentially inaccurate. In my collections, spore width ranges from 3-5 µ for both species, but important macrofeatures do not vary. Agaricus placomyces is somewhat larger than Agaricus pocillator, and has more brown scales and fibers away from the disc. Additionally, it lacks the small, abrupt bulb at the stem base and often (though not always) has brownish or yellowish droplets on the underside of the partial veil when it is still covering the gills.**