Russula fragilis var. fragilis (Pers.) Fr. - Fragile Brittlegill

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Russulales - Family: Russulaceae

Distribution - Taxonomic History - Etymology - Identification - Culinary Notes - Reference Sources

Russula fragilis, the Fragile Brittlegill, is a small and extremely crumbly mushroom with a relatively long stem. In appearance this is a very variable brittlegill: its cap colour can be pink, violet, purple or white, often including a central region tinged with green, yellow and brown. The variety Russula fragilis var. nivea is all white.

Finding an undamaged specimen of this delicate mushroom is far from easy, even though this is a commonly occurring woodland species.

Distribution

This little brittlegill is widespread and very common in Britain and Ireland as well as in other European countries. Its range extends into temperate regions of Asia, and this species is also recorded in parts on North America.

Taxonomic history

Russula fragilis was described in 1801 by Christian Hendrik Persoon, who gave it the binomial scientific name Agaricus fragilis. (Most gilled fungi were initially placed in a giant Agaricus genus, but the majority have since been redistributed across several other newer genera leaving only what are commonly referred to as the 'true mushrooms' in the genus Agaricus.) In 1838 the Fragile Brittlegill was transferred to the Russula genus by the great Swedish mycologist Elias Magnus Fries, whereupon its scientific name became Russula fragilis.

Synonyms of Russula fragilis include Agaricus fallax Schaeff., Agaricus fragilis Pers., Agaricus linnaei var. fragilis (Pers.) Fr., Russula bataillei Bidaud & Reumaux, Russula emetica ssp. fragilis (Pers.) Singer, Russula emetica var. fragilis (Pers.) Quél., and Russula fragilis var. fallax (Schaeff.) Massee.

Etymology

Russula, the generic name, means red or reddish, and indeed many of the brittlegills have red caps (but many more are not, and several of those that are usually red can also occur in a range of other colours!). The specific epithet fragilis means fragile, of course, and indeed this just has to be one of the most brittle of brittlegills!

Identification guide

	Cap 2 to 6cm diameter, often noticeably grooved at the margin, the caps are initially convex, then expanding and becoming depressed. Very brittle. Most are violaceous or purple, darker in the centre and sometimes taking on a green tinge when old. The cap flesh white. (A pure white variety, var. nivea is also fairly common.)
	Gills The very brittle gills are adnate, white or pale cream, with toothed edges. (This latter feature is only visible with a magnifying glass.) Stem 2 to 6cm long  and 5 to 10mm in diameter, the stems are white, sometimes tinged yellow near the base. The slightly swollen base is particularly brittle. The white flesh of the stem crumbles very easily.
	Sphaerocycts The brittle flesh contains spherical cells known as sphaerocycts. Show larger image Sphaerocysts of Russula fragilis, Fragile Brittlegill  X
	Spores Globose (almost spherical), 7.5-9 x 6-8µm; ornamented with warts up to 0.5µm tall connected by fine lines to form an almost complete network. Spore print White.
Odour/taste	Slight fruity odour; acrid taste.
Habitat & Ecological role	In broadleaf woodland and sometimes also in coniferous woodland, preferring damp, well shaded places; usually scattered rather than in large groups. In common with other members of the Russulaceae, Russula fragilis is an ectomycorrhizal mushroom.
Season	August to October in Britain and Ireland.
Similar species	Russula atropurpurea, the Purple Brittlegill, is much larger with a very dark, almost black cap centre and pale cream gills; its stem base is rusty brown.

Culinary Notes

The Fragile Brittlegill is bitter tasting and generally considered to be inedible.

Reference Sources

Pat O'Reilly (2016). Fascinated by Fungi, First Nature Publishing

Geoffrey Kibby (2011).The Genus Russula in Great Britain, published by G Kibby.

Roberto Galli (1996). Le Russule. Edinatura, Milan.

Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers. (2008). Dictionary of the Fungi; CABI.

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.

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