{{Short description|Species of mushroom-forming fungus}} {{Speciesbox | image = Russula caerulea 342205542.jpg | taxon = Russula caerulea | authority = Fr. (1838) | synonyms_ref = <ref name="Species Fungorum synonymy"/> | synonyms = *''Agaricus caeruleus'' {{small|Pers. (1801)}} *''Russula amara'' {{small|Kučera (1927)}} }} {{mycomorphbox | name = ''Russula caerulea'' | whichGills = adnexed |whichGills2= free | capShape = convex |capShape2=umbonate | hymeniumType=gills | stipeCharacter= bare | sporePrintColor=ochre | howEdible=edible }}
'''''Russula caerulea''''', commonly known as the '''humpback brittlegill''', is a member of the genus ''Russula'', whose members are also known as brittlegills. It is a dark vinaceous or purple-colored edible mushroom, and grows with coniferous trees in late summer and autumn. It is found in Europe and North America.
==Taxonomy== First described by mycologist Christian Hendrik Persoon in his 1801 work ''Synopsis methodica fungorum'' as ''Agaricus caeruleus'', its specific epithet is the Latin ''caeruleus'' meaning "blue".<ref>{{cite book|author = Simpson DP| title = Cassell's Latin Dictionary | publisher = Cassell Ltd.| date = 1979|edition = 5|location = London|page = 883| isbn=0-304-52257-0}}</ref> It was transferred to the genus ''Russula'' in 1838 by the Swedish father of mycology Elias Magnus Fries. The 1927 name ''Russula amara'' by Kučera is a synonym.<ref name="Species Fungorum synonymy"/>
==Description== The cap is {{convert|3|–|10|cm|in|round=0.5|abbr=on}} in diameter. It is dark purplish-brown, with a dark, sometimes almost black centre. At first it is convex, or even nearly bell-shaped, but later flattens. It nearly always retains a broad pointed boss (umbo) in the cap centre which is a profile that is almost unique within the genus. The cap skin peels to two-thirds, and it later has a furrowed margin. The firm, white stipe is {{convert|4|–|9|cm|in|round=0.5|abbr=on}} high, {{convert|1|–|2|cm|in|round=0.5|abbr=on}} wide and narrowly club-shaped. The gills are adnexed to almost free, and are pale ochre, giving a spore print of the same colour. They are quite closely spaced initially. The flesh is white and tastes mild, but the cap skin is bitter on the tongue.<ref name=Phillips06>{{cite book| author = Roger Phillips | year = 2006 | title = Mushrooms | publisher = Pan MacMillan | isbn = 0-330-44237-6|page = 25}}</ref>
Spores are ellipsoid and ornamented. Size 8-9 μm × 6.5-8 μm.<ref>{{cite book |date=2012 |first=Stefan |first2=Chris |first3=Denys |isbn=978-0-00-746648-1 |last=Buczacki |last2=Shields |last3=Ovenden |location=London |publisher=HarperCollins Publ |title=Collins Fungi Guide: The most complete field guide to the mushrooms & toadstools of Britain & Ireland}}</ref>
===Similar species=== ''Russula atropurpurea'' (Krombh.) Britzelm is infrequent with conifers, preferring deciduous woods, and forests. Its cap is never umbonate, but usually depressed.
''Russula viscida'' Kudrna has no umbo either, and is very rare. The cuticle of the cap hardly peels at all.<ref name=Phillips06/>
==Distribution and habitat== ''Russula caerulea'' appears in late summer and autumn. It is widespread in the northern temperate zones, Europe, Asia, and North America. It is probably mycorrhizal with pine trees (''Pinus''), on sandy soils.
==Edibility== This mushroom is edible, but has a bitter cap skin after chewing.<ref name=Phillips06/>
== Image gallery == {{Gallery | Russula caerulea 342205538.jpg | Cap, gills and stipe | Russula caerulea 342205544.jpg | Spores }}
==See also== *List of ''Russula'' species
==References== {{Reflist|refs=
<ref name="Species Fungorum synonymy">{{cite web |title=Synonymy: ''Russula caerulea'' Fr., Epicr. syst. mycol. (Upsaliae): 353 (1838) |url=http://www.speciesfungorum.org/GSD/GSDspecies.asp?RecordID=193054 |publisher=Species Fungorum |access-date=2 May 2021}}</ref>
}}
{{Taxonbar|from=Q999441}}
caerulea Category:Fungi of Europe Category:Fungi of North America Category:Fungi of Asia Category:Edible fungi Category:Fungus species