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Cyanosporus subcaesia (A. David) B. K. Cui, L. L. Shen & Y. C. Dai - Blueing Bracket

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Polyporales - Family: Fomitopsidaceae

Cyanosporus subcaesia, tiers of brackets

Pale at first, this annual bracket fungus, which can appear singly or in rows or tiers, turns blueor blue-grey, most noticeably on its upper surface, as it ages.

Dead wood from broadleaf trees such as oaks, beeches and alders are the staple diet of this wood-rotting fungus.

Cyanosporus subcaesia, side view

Distribution

Widespread and fairly common in Britain (rather more common in southern England) and in Ireland, Cyanosporus subcaesia is found throughout most of mainland Europe but is most common in central and northern Europe. This species is also recorded in parts of Asia.

Taxonomic history

This bracket fungus was described scientifically in 1974 by French (?) mycologist Alix David, who established its basionym when he gave it the binomial name Tyromyces subcaesius. The Blueing Bracket was transferred to its present genus in paper published in Persoonia in 2019 by B. K. Cui, L. L. Shen & Y. C. Dai, at which point its scientific name became Cyanosporus subcaesius..

Synonyms of Cyanosporus subcaesius include Tyromyces subcaesius A. David, Oligoporus subcaesius (A. David) Ryvarden & Gilb., Postia subcaesia (A. David) J├╝lich, and Spongiporus subcaesius (A. David) A. David.

Cyanosporus subcaesia, top view

Etymology

Postia, the genus name, comes from the Latin noun postal, meaning a place. The specific epithet subcaesia means faintly sky blue and is a reference to the colour of the upper (infertile) surface of mature specimens of this bracket fungus.

Identification Guide

Hairy cap of Cyanosporus subcaesia

Cap

The roughly semicircular fruitbodies are typically 1 to 5cm across and up typically 2 to 3cm thick, and the upper surface is covered in fine hairs and radial wrinkles that create a slightly wavy margin. The upper surface is white initially but develops a blue-grey tinge, especially towards the margin, as it matures. Often in fusing overlapping rows and tiers. Flesh white, fibrous.

 

Fertile surface of Cyanosporus subcaesia

Tubes and Pores

The rounded, elongated slit-like or labyrinthine pores are whitish, 3 to 5mm deep, and spaced 5 to 6 per mm.

 

Spores

Cylindrical to allantoid (sausage-shaped), smooth, 4.5-5.5 x 1-1.5µm; inamyloid.

Spore print

White or very faintly pale blue.

Odour/taste

Not distinctive.

Habitat & Ecological role

The Blueing Bracket is saprobic mainly on the well rotted dead wood of hardwood trees including Quercus, Fraxinus, Fagus, Corylus and Betula.

Season

Brackets are visible throughout most of the year, but they release their spores in late autumn.

Similar species

Postia caesia is similar and grows of dead conifer timber in wet locations.

Postia alni is very similar and occurs on dead wood of broadleaf trees; it produces smaller brackets with a much less hairy upper surface, but even some experts continue to question whether this is a species truly distinct from Cyanosporus subcaesius.

Culinary Notes

These bracket fungi are generally considered to be edible.

Reference Sources

Mattheck, C., and Weber, K. Manual of Wood Decays in Trees. Arboricultural Association 2003.

Pat O'Reilly, Fascinated by Fungi, 2011.

BMS List of English Names for Fungi

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.

Acknowledgements

This page includes pictures kindly contributed by Barry Gall.

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