E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Section Arvenses. Agaricus augustus is distinguished by 1) large size, 2) a yellow staining cap with fibrils or scales that are dark brown to warm brown or tawny brown, 3) gills that are pallid, sometimes briefly pinkish, and then grayish brown and chocolate brown from spores, 4) a stem that is smooth in its upper part and shaggy with white or brown-tipped scales in its lower part, 5) a prominent skirt-like ring, 6) an almond odor, and 7) growth in disturbed soil. Agaricus perrarus Schulz. is given as a synonym by Breitenbach(4) and other European authors, but A.H. Smith showed that the material he named A. perrarus was different and this material has been renamed Agaricus smithii Kerrigan. |The odor of A. augustus is due to benzaldehyde which can be perceived as anise by some or as the usual almond odor (Wood(1)). |A. augustus is common in the Pacific Northwest.

It has been found in BC, WA, OR, and CA. There are collections from BC at the University of British Columbia and from WA, OR, and VA at the University of Washington. Lincoff(2) says it is found from BC to CA, in the Rocky Mountains, and reportedly in eastern North America. Breitenbach(4) give the distribution as North America, Europe, Asia, and North Africa.

Cap:
7-30(40)cm across, "usually marshmallow-shaped but sometimes convex", expanding to flat or with an uplifted margin; "covered with numerous dark brown to warm brown or tawny-brown fibrils or fibrillose scales" on a white background that usually becomes yellowish, buff, or ocher when old, "giving an overall golden tone to many mature specimens", center often darker; may bruise yellow when rubbed, especially when young; dry, "surface sometimes breaking up into warts in dry weather", (Arora), 8-32cm across, at first nearly spherical or more cylindric, then convex to broadly convex, finally flat to uplifted, margin sometimes wavy; at first medium brown, later darker brown, or dark brown when old, on whitish background, sometimes becoming bright yellow when bruised or cut, often tawny when old, typically yellowish to orange after drying; dry, appressed-fibrillose becoming appressed-fibrillose-squamulose when mature, scales about 0.5cm long, with pointed tips, "or alternatively forming large patches of fibrils", or sometimes areolate [cracked like dried mud] if dried out, (Kerrigan)

Flesh:
thick, firm, white, (Arora), up to 3cm thick, firm when young; white, sometimes becoming yellow near cuticle after exposure, in stem white, occasionally yellowish somewhat near cuticle or base when cut, (Kerrigan)

Gills:
free when mature, close; pallid, sometimes briefly pinkish, finally turning grayish brown, eventually chocolate brown to blackish brown, (Arora), free, close, up to 2cm broad; pallid when young, occasionally briefly pink, later grayish brown, finally dark blackish brown, with pallid margin, (Kerrigan(1))

Stem:
8-35cm x 1-4(6)cm, equal or widening slightly downward, rather tough, fibrous, base usually deep in ground; "white but often aging or bruising yellowish"; "smooth above the ring, sheathed with white or brown-tipped scales below (but these often wearing away in age)", (Arora), 10-35cm x 1-4cm, equal, rarely widened in lower part, stuffed-hollow, somewhat fibrous, base deeply rooted; white, sometimes briefly pink near top after veil rupture, becoming pale yellowish when old; bald in upper part, under humid conditions completely covered in lower part with erect floccose squamules [woolly-cottony fine scales], (Kerrigan(1))

Veil:
"membranous, with white to brown cottony patches on underside (but these sometimes disappearing)", forming a large, ample, superior, skirt-like ring, (Arora), "veils forming a thick, broadly flaring, pendant, subapical to supramedian, white annulus", partial veil smooth above, 0.1-0.2cm thick, universal veil a loosely interwoven, floccose-rimose layer, with a zone of thicker (about 0.2-0.3cm thick) patches near ring margin, or sometimes appendiculate [hanging] on cap margin, patches white to colored as cap, universal veil also leaving "a continuous covering of deciduous, white or brown-tipped, pointed, fibrillose-floccose squamules" below ring, (Kerrigan(1)), double, thick patches of pointed tips on underside, (Chariton)

Odor:
"sweet (like almond extract), especially when young", (Arora), of almonds (Kerrigan(1)), pleasant, of almonds, (Phillips), anise (Hotson), anise or almonds (Miller)

Taste:
pleasant, of almonds, (Phillips), mild (Miller)

Microscopic spores:
spores 7.5-10 x 5-6 microns, elliptic, smooth, (Arora), spores (6.8)7.7-9.4(10.5) x (4.5)5.1-6.0(6.8) microns, elliptic approaching elongate, dark brown, hilar appendix prominent, germ pore not evident; basidia 4-spored, 18-22 x 9-10 microns, clavate to broadly clavate; cheilocystidia abundant, continuous, 6-30 x 6-22 microns, mostly elongate, sometimes shorter, to nearly spherical, short-catenulate, (Kerrigan(1)), basidia predominantly tetrasporic (Kerrigan(3))

Spore deposit:
chocolate brown (Arora)