August Salt Spring Island Fungus of the Month: Tapinella Atrotomentosa

Tapinella atrotomentosa, the velvet-footed pax, is one of the earliest of "autumn" fungi, an omen of the beauty to come.  It often appears in late august and is finished by October. It is a dense and sturdy large wood-rotting fungus usually found on douglas fir stumps. This mushroom is a gilled bolete, which may explain its solidity; boletes usually have sturdier flesh than agarics. It has gills that go most of the way down the stem, and fine dark fuzz at the base of the stem, which gives it both its scientific name - "atrotomentosa" means "black haired" - and the "velvet" of its common name.

observation by dianalynn1

Unlike many other fungi, the velvet-footed pax does not rely on being eaten by animals to spread its spores. When it is damaged, it defends itself at the site of the injury by converting innocuous leucomentins into a chemical called atrotomentin, which discourages insects from eating the fungus.  Its spores are spread by wind alone.

observation by caladri

Atrotomentin is what gives the mushroom cap its lovely cinnamon-brown colour, but it is not the only pigment in the mushroom. This species also produces orange flavomentin and violet spiromentin. Its attempts to remain slug and insect-free leave it full of hidden colour. When you cut the mushroom, the inside is greyish, not the brown or cream you would expect. 

Michael Kuo of MushroomExpert.com says:

Although chemical testing is probably not needed in order to successfully identify Tapinella atrotomentosa, its reaction to common household ammonia is so striking, purple, and unexpected that I recommend the test just for the fun of it.

This species can be used to dye wool or cloth, though with so many pigments and enzymes that transform them, the results are very dependent on temperature and pH, and can be quite unpredictable. It can impart a green, blue, grey, purple, or brown colour. This year, we tried dyeing with this mushroom, and while early results were faintly purple, the final colour was a less interesting tan, though it did retain a slight purple undertone.

Here is a beautiful skein of purple-grey yarn dyed with Tappinella atrotomentosa by Anna Kika

You can see even more colours of wool dyed with velvet-footed pax, and instructions on dying with it, on Shroomworks, a Sunshine Coast mushroom blog.

This fungus also starred in a photograph accompanying an article in the Driftwood about people on Salt Spring Island using iNaturalist.

Posted on November 2, 2020 02:01 AM by corvi corvi

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