Pluteus aurantiorugosus (Trog) Sacc.

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

Pluteus aurantiorugosus

Pluteus aurantiorugosus is a wood-rotting fungus that occurs mainly on broadleaf (hardwood) stumps and large logs of buried hardwood timber, mainly of well-rotted elm trees. This attractive mushroom can appear at any time from early summer right through to the end of autumn.

Pluteus aurantiorugosus, southern England

Distribution

In Britain this is an uncommon find and largely restricted to southern England a South Wales; it has also been recorded at least once in Northern Ireland. This wood-rotting mushroom is also found in many parts of mainland Europe.

Taxonomic history

The basionym of this species was established when the Willow Shield was described in 1857 by Swiss mycologist Jakob Gabriel Trog (1781 - 1865), who gave it the name Agaricus aurantiorugosus.

Synonyms of Pluteus aurantiorugosus include Agaricus aurantiorugosus Trog, Pluteus leoninus var. coccineus Massee, Pluteus caloceps G.F. Atk., and Pluteus coccineus (Massee) J.E. Lange.

Etymology

Pluteus, the genus name, comes from Latin and literally means a protective fence or screen - a shield for example!

The specific epithet aurantiorugosus means gold and granular, a reference to the colour and sometimes granular texture of the cap surface.

Identification guide

Cap of Pluteus aurantiorugosus

Cap

Smooth or finely velvety (rugose!) especially towards the centre, flame orange but often more yellow towards the margin, initially convex and usually flattening with a broad umbo, the caps are typically 3 to 7cm in diameter.

The cap flesh is white and firm.

Cap cuticle cells, Pluteus aurantiorugosus

Pileipelis

The cap cuticle is a cystoderm with inflated, rounded terminal cells.

Gills and stem of Pluteus aurantiorugosus

Gills

White at first, becoming pale pink, the gills are broad, crowded and free.

Cheilocystidia

Gill-edge cystidia are not ornamented with horns.

Stem

Yellowish to pale orange (but paler than the cap) but darker orange towards the base, untapering, 3 to 6mm in diameter and 3 to 8cm long, striate with fine longitudinal fibres. The woolly base is whitish or yellow, and the stem flesh is white or pale yellow and firm.

Spores of Pluteus aurantiorugosus

Spores

Broadly ellipsoidal, smooth, 5.5-7.5 x 4.5-5.5µm, hyaline.

Show larger image

Spore print

Pale pink.

Odour/taste

Not distinctive.

Habitat & Ecological role

Saprobic, usually solitary on long-dead stumps, buried rotting fallen branches and other woody debris of broadleaf trees, particularly elm and sometimes ash.

Season

Fruiting from early summer to late autumn, provided the weather is mild. Most often fruiting from mid summer to mid autumn.

Similar species

Pluteus umbrosus has a darker wrinkled cap and is generally a little smaller.

Pluteus cervinus has a smooth brown or fawn cap.

Culinary Notes

It is not entirely clear to me whether Pluteus aurantiorugosus contains Psilocybin, a hallucinogenic substance, and so I consider it inadvisable to gather these mushrooms for eating. (In any case their rarity in Britain and Ireland makes collection not just impractical but ecologically quite inappropriate.)

Pluteus aurantiorugosus, caps and stems

Reference Sources

Alfredo Justo, Andrew M. Minnis, Stefano Ghignone, Nelson Menolli Jr., Marina Capelari, Olivia Rodríguez, Ekaterina Malysheva, Marco Contu, Alfredo Vizzini (2011). 'Species recognition in Pluteus and Volvopluteus (Pluteaceae, Agaricales): morphology, geography and phylogeny'. Mycological Progress 10 (4): 453–479.

Orton, P.D. (1986). British Fungus Flora: Agarics and Boleti. Vol 4. Pluteaceae: Pluteus & Volvariella. Royal Botanic Garden: Edinburgh, Scotland.

Funga Nordica, Henning Knudsen and Jan Vesterholt, 2008.

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.

Acknowledgements

Pictures on this page are shown by kind permission of Simon Harding and Zoran Bovovic.

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