23 Feb 2018

Colourful Wood: Spalting Fungi

by Jan Thornhill

Chlorociboria produces blue-green fruit bodies.
Chlorociboria produces gorgeous blue-green fruit bodies.
It’s easy to forget while collecting fungi that the ones we find growing on wood and elsewhere are only their fruiting bodies—the actual organism is usually hidden, its mycelium buried deep in wood or soil. But the microscopic mycelium of some wood-loving fungi make it very clear just how large an area they’ve taken over by staining the wood they’ve colonized. This staining, which can sometimes be dark lines, other times extensive areas of colour, is called spalting.

Blue-green wood spalted by the cup fungus Chlorociboria.
Wood stained blue-green by the fungus Chlorociboria.
The fairly common Chlorociboria aeruginascens and its sister C. aeruginosa, which can only be differentiated microscopically, stain the wood they’ve colonized a stunning blue-green with the pigment xylindein. This beautiful blue wood has been used by woodworkers since at least the 15th century, primarily in inlays (see examples here). It’s such a striking colour that studies are underway to find a way to inoculate various forest trees with Chlorociboria to enhance the value of the lumber. I used to be impressed that anyone had ever found a piece of this blue wood in good enough shape to use for anything other than as a conversation piece. Until last year, whenever I found itthe wood was already so decomposed I could easily pull it apart with my fingers.

And then I came across this oak tree that had fallen across a park path:

Ruby & Fritz inspecting spalted log
Though the colour of this Chlorociboria spalted log is a much
darker than usual, the wood is still usable.
And then I discovered a much more uncommon disc fungus that also stains wood.

Patinellaria sanguinea produces tiny black discs and stains wood coral red
Patinellaria sanguinea stains wood coral red. 
I had found a mystery purple crust growing on a branch in the fall. I couldn't get any spores from it to aid identification, so I wet it and put it in a plastic container, hoping that by giving it a little warmth and moisture it might revive and offer me some spores. The only thing that happened was that it started decaying. I was about to relegate the branch to the kindling pile when I noticed that in a couple of places its surface was oddly coloured with reddish-pink spiderwebby fuzz. I assumed this was just an unusual mold, but when I got out my loupe to inspect it I was surprised to see a multitude of minute blackish discs embedded in it. Hmm.

Patinellaria sanguinea under microscope
Amazing colour of "black" Patinellaria sanguinea fruit bodies under the microscope.
When I put a sample under the microscope I immediately saw that the pink fuzz was not a mold, but a hyphal mat, or subiculum, that clearly belonged to the blackish discs. Not only that, but, when sectioned, the “black” discs were actually quite strikingly coloured. There were even some asci and spores.

Wood stained, or spalted, by Patinellaria sanguinea 
None of my books gave me a name, so I got out my knife out and carved a few chunks off the branch to dry for later study. It was only then that I realized my little ascomycete had stained the wood a gorgeous coral red. 

Days passed. I was doing an unrelated image search for another minute black disc, Patellaria atrata, when halfway down the page a picture jumped out at me. It clearly showed exactly what I had accidentally grown—mini blackish discs with a pinkish red subiculum. And they had a name. Panitellaria sanguinea

I have not been able to find out much about this little curiosity, which has also been known as Durella sanguinea and Peziza sanguinea, other than that it’s rare, grows in North America and Europe, and apparently prefers hardwoods. 

A number of common wood-decaying fungi spalt wood with black
lines – barriers that keep other fungi out of their "territory."
Spalted wood created by several different
species, including Chlorociboria.

(N.B. This post appeared in a slightly different form on my blog, Weird & Wonderful Wild Mushrooms)

More Info:

Tom Volk’s Chlorociboria page
Panitellaria sanguinea on Mycoquebec
Panitellaria sanguinea on Mycokey
Robinson, S.C., Tudor, D., Snider, H., Cooper, P.A. 2012. Stimulating growth and xylindein production of Chlorociboria aeruginascens in agar-based systems. AMB Express 2(15).
More about spalting: Northern Spalting
George Grant Hedgcock. "Studies Upon Some Chromogenic Fungi which Discolor Wood." St. Louis, 1906

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