Public Description of Agaricus augustus Fr.

Title: Public Description
Name: Agaricus augustus Fr.
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Description status: Unreviewed

Taxonomic Classification:

Domain: Eukarya
Kingdom: Fungi
Phylum: Basidiomycota
Class: Agaricomycetes
Order: Agaricales
Family: Agaricaceae

General Description:

The fruiting bodies of Agaricus augustus are large and distinctive agarics. The cap shape is hemispherical during the so-called button stage, and then expands, becoming convex and finally flat, with a diameter of up to 22 cm. The cap cuticle is dry, and densely covered with concentrically arranged, brown-colored scales on a white to yellow background.

The flesh is thick, firm and white and may discolor yellow when bruised. The gills are crowded and pallid at first, and turn pink then dark brown with maturity. The gills are not attached to the stem — they are free. Immature specimens bear a delicate white partial veil with darker-colored warts, extending from the stem to the cap periphery.

The stem is clavate up to 20 cm tall, and 4 cm thick. In mature specimens, the partial veil is torn and left behind as a pendulous ring adorning the stem. Above the ring, the stem is white to yellow and smooth. Below, it is covered with numerous small scales. Its flesh is thick, white and sometimes has a narrow central hollow. The stem base extends deeply into the substrate.

The mushroom’s odor is strong and nutty, of anise or almonds, which can be associated with the presence of benzaldehyde and benzyl alcohol.4 Its taste has been described as not distinctive.

Under a microscope, the ellipsoid-shaped spores are seen characteristically large at 7–10 by 4.5–6.5 μm. The basidia are 4-spored. The spore mass is colored chocolate-brown.25

Diagnostic Description:
A. subrufescens closely resembles A. augustus in appearance. However, A. subrufescens produces smaller spores, sized 6–7.5 by 4–5 µm.


occurring throughout Europe, North America, North Africa and Asia.

deciduous and coniferous woods and in gardens and by roadsides

Look Alikes:
Agaricus subrufescens




Agaricus augustus Fr., Epicr. syst. mycol. (Upsaliae): 212 (1838) [1836-1838]

Agaricus augustus var. albus M.M. Moser, in Gams, Kl. Krypt.-Fl., Rev. Edn 5 (Stuttgart) 2b/2: 230 (1983)
Agaricus augustus Fr., Epicr. syst. mycol. (Upsaliae): 212 (1838) [1836-1838] var. augustus
Agaricus augustus var. perrarus (Schulzer) Bon & Cappelli, Docums Mycol. 13(no. 52): 16 (1983)
Agaricus peronatus Massee, Brit. Fung.-Fl. (London) 1: 415 (1892)
Agaricus perrarus Schulzer, Verh. zool.-bot. Ges. Wien 29: 493 (1880)
Fungus augustus (Fr.) Kuntze, Revis. gen. pl. (Leipzig) 3(2): 479 (1898)
Fungus peronatus Kuntze, Revis. gen. pl. (Leipzig) 3(2): 480 (1898)
Pratella augusta (Fr.) Gillet, Hyménomycètes (Alençon): 561 (1878)
Psalliota augusta (Fr.) Quél., Mém. Soc. Émul. Montbéliard, Sér. 2 5: 255 (1872)
Psalliota peronata Massee, Brit. Fung.-Fl. (London) 1: 415 (1892)
Psalliota perrara (Schulzer) Bres., Fung. trident. 1(1): 82 (1881)

Description author: Michael Wood (Request Authorship Credit)
Description editor: walt sturgeon