Oudemansiella mucida (Schrad.) Höhn. - Porcelain Fungus

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

Oudemansiella mucida - Porcelain Fungus

Oudemansiella mucida (increasingly being referred to by the synonym Mucidula mucida), the Porcelain Fungus, is specific to beech wood. It appears in autumn on dead trunks and on fallen branches, and occasionally it also grows on dead branches high up in living trees.

This beautiful fungus is featured on the front cover of the new edition of Fascinated by Fungi.

Distribution

Common and widespread in Britain and Ireland, Oudemansiella mucida occurs throughout northern Europe, but in southern Europe where Beech is not found the Porcelain Fungus is also absent.

Mature Porcelain Fungi on a Beech branch

I have seen fallen Beech trees literally covered in Porcelain Fungus (also referred to as Porcelain Muchroom or as Beech Tuft), and few other fungi seem to get much of a nibble. This, it has been discovered, is because Oudemansiella mucida releases a powerful fungicide that deters or even anihilates competitors.

Known as a strobilurins, these kinds of anti-fungal agents are used increasingly to protect crops from attacks by powdery mildews and other microfungi. Although subsequently improved upon by industrial chemists, the first strobilurin fungicides were isolated from wood-rotting mushroom fungi such as Oudemansiella mucida and, in particular, another white-spored wood-rotting species that goes by the name of Strobilurus tenacellus (commonly known as the Pinecone Cap), from which these kinds of agents get their common name 'strobilurins'.

When these mushrooms grow underneath a large branch or a fallen trunk, the stems curl so that the caps are all held horizontal and with their gills facing downwards - as seen here.

How the stems curl when Oudemansiella mucide grown underneath a branch

Taxonomic history

In 1794 the German botanist and mycologist Heinrich Adolf Schrader (1767-1836) described the Porcelain Fungus and gave it the scientific name Agaricus mucidus. (Most of the gilled mushrooms were included initially in the genus Agaricus!) Its present accepted name dates from 1909, when Austrian mycologist Franz Xaver Rudolf von Höhnel (1852 - 1920) transferred this species to the genus Oudemansiella.

Synonyms of Oudemansiella mucida include Agaricus mucidus Schrad., Collybia mucida (Schrad. : Fr.) Quél., Armillaria mucida (Schrad.) P. Kumm., and Mucidula mucida (Schrad.) Pat.

Etymology

The genus Oudemansiella was established in 1881 by Italian-Argentinian mycologist Carlos Luigi Spegazzini (1858 - 1926) and named in honour of the Dutch mycologist Cornelius Anton Jan Abraham Oudemans (1825 - 1906).

The specific epithet mucida refers to the layer of transparent mucus that covers the caps of these mushrooms.

Identification guide

Porcelain fungus on a beech tree

The Porcelain Mushroom, Oudemansiella mucida, is also sometimes referred to by the common name of Poached Egg fungus - a reference to the white of the egg rather than the yolk, of course!

This fungus is saprobic or weakly parasitic upon beech trees, and on breezy days in autumn it is not unusual to see what appear to be tiny parachutes falling from high branches after the fungi have been dislodged by the wind.

Cap of Oudemansiella mucida

Cap

2 to 8cm in diameter, semi-transparent and white, the caps of this lovely mushroom are rounded and tend to remain broadly domed rather than completely flat as the fruiting bodies mature. The gills show through the thin cap flesh, giving the margin a striate appearance.

A mucous slime covers the cap during wet weather.

Gills of Oudemansiella mucida

Gills

Adnate, broad and very distant, the gills of the Porcelain Mushroom are translucent white at first, sometimes developing an ochre tint as the fruiting body ages.

Stem of Oudemansiella mucida

Stem

Slender, with a substantial stem ring, the stems are 3 to 7mm in diameter, up to 8cm long, and often curved so as to bring the cap to the horizontal in situations where large tufts of Porcelain Mushrooms are attached to a small area of the host.

Above the ring, the stem is white; below the ring it is slightly striate and greyish.

Spores of Oudemansiella mucida

Spores

Globose to subglobose, smooth, very thick-walled, 14-18 x 11-16 μm.

Show larger image

Spore print

White.

Odour/taste

Not distinctive.

Habitat & Ecological role

Saprobic on stumps, trunks and branches of dead beech trees; also weakly parasitic upon living beech trees, often very high up.

Season

July to October in Britain and Ireland.

Similar species

There are many other white mushrooms, but none with such translucency and greasy caps that are so specifically associated with beech trees.

Sunlight shining through Porcelain Mushrooms, Aviemore, Scotland

Culinary Notes

Provided that the skin is thoroughly washed (or peeled from the caps) to remove the mucus, these mushrooms are edible, although their slimy covering is probably enough to put most people off. Only larger caps are worth collecting, because the flesh is thin and insubstantial.

Above: Sunlight shining through the translucent caps of Porceain Mushrooms on a fallen beech trunk - Aviemore, Scotland.

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.

Other web pages about this species

The Wildlife Trusts (UK)

Roger Phillips (UK)

Top of page...


Fascinated by Fungi, 2nd edn, hardback

If you have found this information helpful, we are sure you would also find our book Fascinated by Fungi by Pat O'Reilly very useful. Author-signed hardback copies at a special discount price are available here...

Other nature books from First Nature...