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Agaricus bohusii Bon - Medusa Mushroom

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

Agaricus bohusii, southern England

Agaricus bohusii is one of the most attractive of the Agaricus species - the true mushrooms, as some peoople call them. Although occasionally occurring singly, this species is most often seen fruiting in fasciculate groups with the stem bases conjoined at a common point. The common name Medusa Mushroom refers to the Greek gorgon, a beast in the form of a woman with snakes instead of hair.

Conjoined stem bases of Agaricus bohusii

The curved stems of conjoined Agaricus bohusii mushrooms have a vaguely snake-like appearance.

Agaricis bohusii, mature specimens

Distribution

Agaricus bohusii is a rare find in Britain and Ireland; it occurs also in parts of mainland Europe. The specimens shown on this page were photographed in southern England.

Agaricus bohusii, group

Taxonomic history

This mushroom was first described and validly named in 1983 by the French mycologist Marcel Bon (1925 - 2014), who gave this species the binomial scientific name Agaricus bohusii by which it is still known today.

Synonyms of Agaricus bohusii include Agaricus elvensis M.J. Berkeley & C.E. Broome sensu Cooke.

Etymology

The specific epithet bohusii honours the 20th century Hungarian mycologist Dr. Gabor Bohus.

Identification guide

Mature cap of Agaricus bohusii

Cap

5 to 15 (exceptionally 20) cm across; initially globose becoming convex, with recurved pointed dark brown scales on a whitish or pale brown background; very light brown flesh turning reddish brown and then darkening when cut.

Gills of Agaricus bohusii

Gills

Free; crowded; whitiish or pale pink, turning reddish brown and then dark brown with age.

Stem and ring of Agaricus bohusii

Stem

7 - 20cm long and 1 - 2.5cm diameter., with a tapering base and a superior thick double ring; stem surface very pale brown, smooth above the ring and fibrous and somewhat darker brown below.

Spore of Agaricus bohusii

Spores

Subglobose to ovoid, smooth, 5 - 7 x 4.5 - 6µm.

Show larger image

Spore print

Chocolate brown.

Odour/taste

Odour faintly mushroomy; taste not distinctive.

Habitat & Ecological role

Saprobic, usually fasciculate (in tight bunches) in mixed woodlands, grassy parks, verges and churchyards; occasionally on garden lawns.

Season

July to late October in Britain and Ireland.

Similar species

Agaricus haemorrhoidarius is similar, with grey-brown scales and a stout stem; it occurs under broad-leaved trees, notably oak and beech.

Agaricus augustus, The Prince, is larger and smells of bitter almonds.

Culinary Notes

Although considered a good edible species, Agaricus bohusii is so rare in Britain and Ireland that it is neither appropriate nor worth seeking for culinary use.

Reference Sources

Bon, M. Agaricus bohusii in Documents Mycologiques 13 (49): 56 (1983)

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

Kibby, G. (2011) The genus Agaricus in Britain, 3rd Edition, published by Geoffrey Kibby

BMS List of English Names for Fungi

Funga Nordica: 2nd edition 2012. Edited by Knudsen, H. & Vesterholt, J. ISBN 9788798396130

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.

Acknowledgement

This page includes pictures kindly contributed by Simon Harding.

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