Tricholomopsis rutilans (Schaeff.) Singer - Plums and Custard

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

Tricholomopsis rutilans -  Plums and Custard

Commonly referred to as Plums and Custard or occasionally as the Strawberry Mushroom, Tricholomopsis rutilans is, nevertheless, a very bitter and inedible fungus. It is always a joy to come across these stately mushrooms, not least because of their habit of colonising buried decaying conifer roots and forming wonderfully photogenic groups.

The bright yellow gills of this mushroom serve as a reminder that gill colour is not a good guide to spore colour; the spores of this species are white.

Tricholomopsis rutilans -  Plums and Custard - young fruitbodies

Distribution

This very beautiful wood-rotting mushroom is found throughout Britain and Ireland as well as in other European countries. Tricholomopsis rutilans is also native to North America, but its occurrence in Australia is thought to be due to its being introduced there.

Taxonomic history

Originally described in 1770 by Jacob Christian Schaeffer and called Agaricus rutilans - most gilled fungi were initially placed in a giant Agaricus genus, now redistributed to many other genera - this species was moved into the new genus Tricholoma by Paul Kummer in 1871. There it remained until 1939, when the famous German-born mycologist Rolf Singer assigned it to its present genus Tricholomopsis (implying that it was very much like a Tricholoma, but not quite close enough!).

Synonyms of Tricholomopsis rutilans include Agaricus rutilans Schaeff., Agaricus xerampelinus Scop., Gymnopus rutilans (Schaeff.) Gray, Tricholoma rutilans (Schaeff.) P. Kumm., and Tricholoma variegatum (Scop.) Sacc.

Etymology

Part of a fairy ring of Plums and Custard mushrooms

The genus Tricholomopsis, established by Rolf Singer in 1939, lies somewhere between the genera Clitocybe (many of the fungi within which were formerly - Classed as Tricholoma species) and Tricholoma, and the term Tricholomopsis means 'similar to a Tricholoma'. (Tricho- as a prefix refers to hair.) The specific epithet rutilans means becoming red, as indeed the caps of Plums and Custard usually do (although generally with a purplish tinge).

The splendid line of Plums and Custard mushrooms shown above was part of a large fairy ring growing on the floor of a spruce forest where old stumps and trunks had rotted to produce a soft wood-rich humus with a mossy covering to hold in the moisture - ideal habitat for all sorts of saprobic mushrooms!

Identification guide

Tricholoma rutilans with pale, crazed caps

Against a background of moss covering old pine stumps or fallen trunks, these large, colourful mushrooms make a spectacular sight, especially when, as is often the case, they occur in large numbers.

In very dry weather the caps sometimes craze into a network of scales, revealing the bright yellow flesh beneath the cuticle.

Cap of tthe Plums and Custard mushroom

Cap

4 to 12cm in diameter, the surface of the caps of Tricholomopsis rutilans is bright egg-yolk yellow and covered with radial streaks made up of tiny purple scales.

Beneath the cap cuticle, the thin flesh is pale yellow.

Convex, sometimes with a shallow central depression, the caps expand and become broadly umbonate or occasionally almost completely flat at maturity.

Gills of Plums and Custard fungus

Gills

Adnate or weakly sinuate, the egg-yolk-yellow gills are broad and crowded.

Despite the brightly coloured gills, this mushroom deposits the white spores that are typical of Tricholomas.

Stem of Tricholomopsis rutilans

Stem

1 to 2cm in diameter, the stems range from 4 to 10cm tall and are often curved away from the stump or trunk from which the fruiting body emerges.

Pale near the apex, the stems are covered in purple-red scales on a white background. Beneath the stem surface the flesh is pale yellow.

Spores of Tricholomopsis rutilans

Spores

Ellipsoidal to subglobose, smooth, 5-7 x 3.5-5.5µm.

Show larger image

Spore print

White.

Odour/taste

Odour of rotten pinewood; taste not distinctive. 

Habitat & Ecological role

Saprobic, on conifer stumps, particularly spruce and pine; far less frequently on broad-leaf stumps.

Season

July to October in Britain and Ireland.

Similar species

The close relative Tricholomopsis decora is yellow or yellow-ochre; it is much less common and in Britain it is largely confined to mountain regions of Scotland, only very occasionally turning up on dead pine wood in the lowlands of England and Wales.

Tricholomopsis rutilans -  Plums and Custard - mature fruitbody on a conifer log

Culinary Notes

Despite its tempting common name and very attractive appearance, Tricholomopsis rutilans is bitter and inedible.

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2016.

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.

Other web pages about this species

Roger Phillips (UK)

Michael Kuo (USA)

Marek Snowarski (Poland)

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