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Summary: features include small size, whitish cap with fibrils or fibrillose scales that are pinkish or yellowish brown at first and become brownish to grayish brown, tendency of cap and stem to become deep yellow, fragile flesh, slight fragile skirt-like ring, anise or almond odor, growth in grass, and small spores; also known as Agaricus megathus; Murrill give distribution New England (including VA, NJ) to TN, west to MI and TX, Hotson and Isaacs for WA, Phillips for OR, Kerrigan for CA; collections from BC deposited at University of British Columbia, CHEMICAL REACTIONS staining bright yellow in 3-15% KOH (Chariton), cap surface staining yellow in KOH (Arora)
Cap: 2-4cm across, "broadly convex to convex-truncate when young, becoming depressed centrally", when old nearly flat; dry, innately fibrillose, fibrils pinkish red, darkening to gray-brown or more dingy, forming appressed to slightly repent fine scales about 0.2cm long and 0.1-0.2cm wide, background whitish to buff, (Kerrigan), 4.5cm across approximately, convex, not umbonate; center brown, elsewhere pallid or whitish, staining deep yellow where bruised; innately fibrillose or with few minute appressed scales, (Hotson), 2-5(8)cm across, convex to flat; dry, "with silky fibrils or fibrillose scales (sometimes very sparse toward the margin)", "fibrils at first pinkish in one form, yellow-brown in another, but in both forms becoming brownish to grayish-brown in age on a whitish to buff background", "yellow to orange stains often developing in age or upon handling", (Arora), "fibrils pinkish-red, in age darkening to gray-brown or darker brown" and "streaked with tiny vinaceous-brown scales; surface bruises saffron yellow to ochraceous", (Chariton), cap exceeding gills markedly, 0.1-0.2cm, (Isaacs)
Flesh: up to 0.4cm thick; white, unchanging or becoming yellowish, in stem white, to salmon orange when old, (Kerrigan), thick, white, unchanging, (but also notes all parts of sporophore staining deep saffron-yellow where bruised), (Hotson), thin, fragile; "white, unchanging or bruising yellowish", (Arora)
Gills: free, close, up to 0.3cm broad, "greyish when young, soon pinkish" (quoted from Peck), finally dark blackish brown, (Kerrigan), crowded, broad, thin; white for a long time, becoming pink then purplish gray, (Hotson), free at maturity, close; "pallid or grayish, then pinkish, finally chocolate-brown or darker", (Arora), finally chocolate brown or red-brown, (Chariton)
Stem: 2.5-3cm x 0.2-0.8cm, equal or very slightly bulbous, narrowly stuffed-hollow, cavity 0.05-0.1cm broad; white, becoming orangish when old or when bruised; finely fibrillose when young, bald when old, (Kerrigan), about 4cm long and 0.8cm wide, short, stout, solid; white, staining deep yellow where bruised; bald, (Hotson), 2-6cm x 0.3-1cm, equal or slightly widened at base, "stuffed or hollow, fragile at maturity"; white or staining yellow to orange upon handling, especially in lower part, (Arora)
Veil: veils sometimes appendiculate, more usually forming a pendant (to intermediate-type), subapical to supramedian white ring, flaring 0.2-0.4cm, partial veil white, loosely interwoven, universal veil a narrow denser zone on ring undersurface, soon becoming orangish, also leaving deciduous fibrils on stem, (Kerrigan), ring "median or inferior, narrow, thin, simple, persistent, white", (Hotson), membranous, thin, "forming a fragile, superior to median ring" or disappearing, ring skirt-like or intermediate, (Arora)
Odor: almond (Kerrigan), distinctly sweet (anise-like or almondy), (Arora), pleasant (Phillips), pleasant, faintly of anise, (Kibby)
Taste: pleasant (Phillips), nutty - almond-like (Isaacs)
Microscopic spores: spores (3.8)4.6-4.9(5.6) x (3.0)3.5-3.8(4.1) microns, elliptic to broadly elliptic, dark brown, hilar appendix fairly prominent, germ pore not evident; basidia 4-spored, 21-25 x 5-7 microns, cylindroclavate, sterigmata 2-3 microns long; cheilocystidia not observed, gill margin fertile, (Kerrigan), spores 5-6 x 4-4.5 microns, (Hotson), spores 4.5-5.5 x 3.5-4 microns, broadly elliptic, smooth, (Arora)
Spore deposit: chocolate brown (Arora)
Habitat / Range
gregarious in lawns, pastures and grassy places, (Kerrigan), single to scattered or gregarious "in lawns, pastures, fields and other grassy or open places", (Arora), prefers short turf especially sandy soils (Kibby)
Agaricus comtulus has a white to yellowish cap that is usually tinged brown or buff at the center but has no colored fibrils on button; Agaricus diminutivus group has reddish-pink to purplish cap, woolly stem and woodland habitat; Agaricus semotus has brown to reddish fibrils on cap and slightly longer stem, and found in woods or under trees; like Agaricus peckii Isaacs nom. prov., never validly published, based on a collection found in Oregon, which Isaacs says "is closely related to A. micromegathus, differing in only one truly distinguishing feature, the larger spores" (5.3-6.5 x (4.4)4.7-5.3 microns)
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2019. E-Flora BC:
Electronic Atlas of the Plants of British Columbia [eflora.bc.ca]. Lab for
Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
13/10/2019 4:11:32 PM
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