Sarcomyxa serotina (Pers.) P. Karst. - Olive Oysterling

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

Sarcomyxa serotina, Olive Oysterling

This is a gregarious mushroom that I see only very occasionally, mostly on fallen trees in well-shaded riverside locations. The cap colour changes considerably with age, but usually there is a very noticeable olive tinge as a clue to its identity.

Distribution

In Britain and Ireland Sarcomyxa serotina is an uncommon sight, as it seems to be throughout mainland northern and central Europe. The Olive Oysterling is reported also from North America.

Young caps of Sarcomyxa serotina, Olive Oysterling

Taxonomic history

This saprobic mushroom was first described validly in scientific literature in 1793 by Christiaan Hendrik Persoon, who gave it the binomial scientific name Agaricus serotinus. It was the Finnish mycologist Petter Adolf Karsten (1834 - 1917) who, in 1891, transferred this species to the genus Sarcomyxa, thus establishing its currently-accepted (by many but not all authorities) scientific name Sarcomyxa serotina.

Synonyms of Sarcomyxa serotina include Agaricus serotinus Pers., Pleurotus serotinus (Pers.) P. Kumm., Agaricus almeni Fr., Pleurotus serotinus var. almeni (Fr.) Bigeard & Guillem., Pleurotus serotinus var. flaccidus J. E. Lange, Acanthocystis serotinus (Pers.) Konrad & Maubl., Panellus serotinus (Pers.) Kühner (the name most often seen in field guides until quite recently), and Hohenbuehelia serotina (Pers.) Singer.

Olive Oysterling with scalloped edge

Etymology

The genus name Sarcomyxa comes from the Greek word särkō-, meaning flesh, and -myxa (again from Ancient Greek via Latin) meaning mucus or slime. Slimy flesh-like mushrooms is a description that seems to fit the bill quite nicely.

The specific epithet serotina comes from serotin- meaning 'late' and is a reference to the appearance of these mushrooms very late in the season, often after the first frosts of winter.

Identification guide

Cap of Sarcomyxa serotina

Cap

3 to 10cm across; half-round or kidney-shaped often with a scalloped incurved margin; convex; slightly downy when young, becoming smoother with age; slimy when wet; olive green, often with violet and brown tones, eventually fading to light brown.

Gills of Sarcomyxa serotina

Gills

Adnate to stem; crowded, initially yellowish becoming browner with age.

Stem

Lateral, stout and up to 2cm long (often absent altogether); usually yellowish but sometimes light brown.

Spores of Sarcomyxa serotina

Spores

Cylindrical to allantoid (sausage-shaped), smooth, 4-5.5 x 1-1.5μm; amyloid.

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Spore print

White.

Odour/taste

Odour not distinctive; inadvisable to taste, as this mushroom is thought to contain carcinogens.

Habitat & Ecological role

Saprobic, solitary, in small groups or in overlapping tiers on rotten wood, most often of broadleaf trees but found also occasionally on conifer timber.

Season

Autumn and winter in Britain and Ireland.

Similar species

Oyster Mushroom Pleurotus ostreatus has a very variable cap colour, sometimes olivaceous, but it has white gills when young and fresh and its spores are very much larger that those of the Olive Oysterling.

Culinary notes

This mushroom is stated in older field guides to be edible but not particularly good; however, some authorities, including Andreas Gminder, now say that it can contain carcinogens. Leave them: there are much nicer, safer mushrooms to eat!

Sarcomyxa serotina, Olive Oysterling, Forest of Dean

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2016.

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.

Olive Oysterling, underside view

Other web pages about this species

Gary Emberger (USA)

Roger Phillips (UK) under synonym Panellus serotinus

Marek Snowarski (Poland) under symonym Panellus serotinus

Acknowledgements

This page includes pictures kindly contributed by Simon Harding and Richard Shotbolt.

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