|Major Groups > Gilled Mushrooms > Dark-Spored > Agaricus > Agaricus bellanniae|
by Michael Kuo
I find this little Agaricus species in grassy edgewoods and disturbed ground in oak-hickory woods in central Illinois, in July and August. It has a pale yellowish brown cap that is covered with tiny fibers and scales, a (proportionally) tall and slender stem that features a thin white ring, and flesh that does not change color when sliced. Its odor is not distinctive. The cap surface turns yellow when a drop of KOH is applied.
DNA results place the collections featured here with a collection from Pittsburgh, Pennsylvania and a collection from Gironde, France, making the range of Agaricus bellanniae transcontinental, although its distribution limits have yet to be established with certainty.
Agaricus bellanniae was featured here from 2007–2018 as "Agaricus species 01," and in Kuo (2007) as "Agaricus species."
Ecology: Saprobic; growing gregariously, or in small arcs or fairy rings, in grass; late summer and early fall; possibly widely distributed from the Great Plains eastward. The illustrated and described collections are from Illinois.
Cap: 3.5–8 cm; convex or a little blocky at first, becoming broadly convex, broadly bell-shaped, or nearly flat, with a shallow central depression; dry; minutely fibrillose-scaly; ground color pale brown, scales medium yellow-brown; at first evenly covered but darker over the center and paler elsewhere at maturity; the margin soft, often whitish; not bruising.
Gills: Free from the stem; close or crowded; short-gills frequent; whitish in buttons, then pink, then slowly becoming medium to dark brown; when in the button stage covered with a thin, white partial veil.
Stem: 3.5–7 cm long; 5–12 mm thick; equal or slightly swollen toward the base; occasionally with a small basal bulb; more or less bald; with a high, fragile, white ring; whitish, discoloring a little brownish on handling or with age, and occasionally bruising slightly pinkish; basal mycelium white.
Flesh: White; unchanging when sliced or, occasionally, becoming slightly pinkish in the stem base.
Odor and Taste: Not distinctive.
Chemical Reactions: KOH on cap surface inconsistent: yellow or, on older caps, negative.
Spore Print: Dark brown.
Microscopic Features: Spores: 6–8 x 4–5 µm; ellipsoid; smooth; thick-walled; brown to golden brown in KOH; brown in Melzer's. Basidia 4-sterigmate. Cheilocystidia absent or basidiole-like; 24–30 x 7–8 µm; clavate to subcylindric; smooth; thin-walled; hyaline in KOH. Pleurocystidia not found. Pileipellis a cutis of hyaline elements interspersed with aggregations of upright, brown-walled elements; elements 5–12.5 µm wide, smooth; terminal cells cylindric with rounded apices.
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Cite this page as:
Kuo, M. (2018, April). Agaricus bellanniae. Retrieved from the MushroomExpert.Com Web site: http://www.mushroomexpert.com/agaricus_bellanniae.html