Agaricus devoniensis P. D. Orton

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Agaricales - Family: Agaricaceae

Agaricus devoniensis

Agaricus devoniensis is a mushroom of sandy places - indeed, in Britain it is rarely seen anywhere but on coastal sand dunes. The lower slopes of dunes close to the dune slacks are likely places for this rather elusive species.

Distribution

Infrequent in Britain and Ireland, Agaricus devoniensis occurs also in many parts of mainland Europe. The specimens shown on this page were photographed on the southeast cost of Portugal.

Agaricus devoniensis vies with the Pavement Mushroom, Agaricus bitorquis, for the title of most boring member of the once mighty Agaricus genus. (In the early days of mycology, virtually all gilled fungi were placed in this genus; most have subsequently been relocated to the other genera such as Cortinarius, Entoloma, Hygrocybe, Pluteus, Tricholoma etc.) What is surprising about this otherwise undistinguished mushroom is the fact that something so substantial can survive in what appears to be an almost entirely barren habitat. Perhaps the fact that death comes to so many creatures that venture into bare sand dunes on baking hot days means that there is always something in the way of organic matter for these and other dune fungi to feed upon.

Taxonomic history

First described in 1960 by British mycologist Peter Darbishire Orton (1916 - 2005), who gave it the scientific name Agaricus devoniensis, this species still retains its original name.

Synonyms of Agaricus devoniensis include Psaliota arenicola (Wakefield & Pearson) Pilat., and Agaricus arenophilus Huijsman.

Etymology

The specific epithet devoniensis was given to this mushroom in 1960 by British mycologist Peter Darbishire Orton and is a reference to the English county of Devon in which it was first recorded.

Identification guide

Cap of Agaricus devoniensis

Cap

Initially convex before flattening and sometimes becoming slightly concave, the silkily smooth white caps range from 4 to 7cm in diameter at maturity.

Gills of Agaricus devoniensis

Gills

Pale pink at first, the free densely crowded gills turn dark brown and eventually almost black as the fruitbody matures.

Stem of Agaricus devoniensis

Stem

3 to 4cm tall and 1 to 2cm in diameter, the white stems are smooth above the narrow, ring-like remnants of the partial veil. The stems are more or less cylindrical but sometimes slightly swollen at the base, which turns slightly reddish when cut or bruised.

The fragile ring is usually ephemeral, and by the time the fruitbody is fully developed there is rarely much evidence of a ring remaining.

Spores of Agaricus devoniensis

Spores

Ovoid or subglobose, 6-7 x 4.5-5.5µm.

Spore print

Deep chocolate brown.

Odour/taste

Taste mild; odour not distinctive.

Habitat & Ecological role

Saprobic, on bare or lightly vegetated areas of coastal sand dunes.

Season

July to October in Britain and Ireland.

Similar species

Agaricus bitorquis, the Pavement Mushroom, is very similar but with a thin double ring; it favours dry, compacted places beside paths.

Agaricus littoralis (Wakefield & Pearson) Pilat. also occurs in sand dunes; its cap is ochraceous brown and the spores are more elongated, typically 7 x 4.5µm, whereas the spores of Agaricus devoniensis are on average about 6.5 x 5µm.

Culinary Notes

Despite its rarity, some people ask only one question about this little mushroom: "Is it edible?" The answer is that it is as edible as any nice meal topped with a liberal sprinkling of sand... you simply have to grit your teeth and get on with it.

Reference Sources

Pat O'Reilly (2016) Fascinated by Fungi; First Nature

The genus Agaricus in Britain, 3rd Edition, self-published, Geoffrey Kibby 2011

BMS List of English Names for Fungi

Dictionary of the Fungi; Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers; CABI, 2008

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi and (for basidiomycetes) on Kew's Checklist of the British & Irish Basidiomycota.

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