Russula caerulea (Pers.) Fr. - Humpback Brittlegill

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

Russula caerulea, Humpback Brittlegill, Scotland

This is one of the very few purplish brittlegills which can usually be identified in the field without resorting to chemical tests. Its umbonate brownish-purple cap is quite distinctive.


This brittlegill is fairly common in pine plantations and under pines in parkland and gardens throughout Britain and Ireland as well as in many other parts of Europe. This brittlegill mushroom is also commonly recorded in North America.

Russula caerulea, Humpback Brittlegill, Scotland

Taxonomic history

The Humpbacked Brittlegill was described in 1801 by Christiaan Hendrik Persoon, who gave it the binomial scientific name Agaricus caeruleus. (Most of the gilled mushrooms were included initially in the genus Agaricus, the contents of which has since been largely dispersed into many other newer genera.) The currently-accepted scientific name Russula caerulea dates from an 1838 publication by the great Swedish mycologist Elias Magnus Fries.

Synonyms of Russula caerulea include Agaricus caeruleus Pers., and Russula amara Kucera.

Russula caerulea, south Wales


Russula, the generic name, means red or reddish, and indeed many of the brittlegills do have reddish caps (but many more of the brittlegill mushrooms are not red, and several of those that are usually red can also occur in a range of other colours!).

The specific epithet caerulea suggests that this mushroom is deep blue, but purple-brown is usually its dominant colour component.

Group of Russula caerulea, southern England

Identification guide

Cap of Russula caerulea, Humpback Brittlegill


4 to 8cm across; various shades of glossy purplish brown or vinaceous brown; convex, with a low central umbo; peeling typically 1/2 to 2/3 to the centre.

Gills and stem of Russula caerulea, Humpback Brittlegill


Cream, becoming ochre with age.


3.5 to 6cm tall and 0.7 to 1.4cm dia; white.



Ellipsoidal, 8-9 x 6.5-7.5µm, ornamented with sharp warts up to 1.2µm tall with a few connecting lines but not forming a reticulum.

Spore print

Dark yellow .


Odour not distinctive

Taste of gills and cap flesh mild; cap cuticle bitter.

Habitat & Ecological role

Mycorrhizal with pine trees.


July to November in Britain and Ireland.

Russula caerulea, Humpback Brittlegill, Wales

Culinary Notes

Russula caerulea is reported to be edible.

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.

English Names for fungi; British Mycological Society, 2013.

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.

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