Bjerkandera adusta | Smoky Bracket

The Smoky Bracket

A shelf that marks at a touch

This fungus grows on dead wood. It forms flat shelves. Shelves stack in rows. Each one is thin and tough, though it lasts for months.

Its top is grey to pale brown. Its underside is darker. However, that dark surface gives the species its name. Because the pore surface is grey and smoky, the shelves look as if they have been dusted with soot from a fire.

Touching the pores leaves a black mark. This is the smoky bracket.

Family tree

Meruliaceae, wood-rotting fungi

This fungus belongs to the family Meruliaceae. Willdenow described it in 1787. He gave it a different name. Karsten moved it in 1879.

That genus name honours a botanist, though few modern guides use it. Birch Polypore shares the same order. So do thousands of other wood rotters. The group has been split and rebuilt many times, since pore shape alone cannot settle the family tree, and genetic work keeps shifting the branches.

Most of its relatives cause the same white rot. Few of them, however, blacken on contact.

10 cm of thin grey shelf

How to tell one

Shelf width runs 2 cm to 10 cm. Thickness stays under 1 cm. A single shelf is flat and tough. Several fuse into a broad crust.

The upper face feels velvety, though the rim is smooth. It shows faint zones of grey and cream. Pores are tiny and round, while the tubes behind them run deep. They number 3 to 4 per mm.

The pore surface starts pale, then blackens with age or a scratch. Because the flesh is thin and dry, the shelf stays hard even after years of rain and frost. Its smell is faint and fungal.

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Dead hardwood and old orchards

Where it lives

Dead hardwood is the main host. Beech and birch top the list. Oak, hazel, and willow also work. Stumps and fallen logs hold most, but it also climbs trunks.

Sometimes it grows on living trees. Fruit orchards often carry it. It appears in woods and parks alike, yet it rarely grows on conifers. This species is common across Europe and North America.

Asia and parts of the south also have it. Although it prefers cool woodland, it tolerates long dry spells and returns whenever damp wood becomes available again.

Dead timber

What it eats

It feeds on wood. Enzymes break down lignin first. Cellulose follows. That process leaves the wood pale and soft.

So the rot is called white rot. Unlike brown rot fungi, it does not leave a dark crumbly residue. It also takes sugars from the wood. Water and minerals come from the log.

Its enzymes spill into the wood around it, since they work outside the fungal threads and drift through the damp timber. Those same enzymes, however, interest chemists.

Spores from the pores

The breeding cycle

Spores form on the pore surface. Each spore is tiny and smooth. Millions are released in a season. Wind carries them to new wood, though most fail.

A spore lands on a wound or a stump. It sends out threads. Two threads must meet to breed, while a single one can only wait. Then the pair builds a shelf.

Fruiting bodies appear in late summer. Fruiting bodies can return for several years, since the threads inside the log keep growing quietly through the timber all year round.

No global rating

Conservation

No global IUCN entry covers this fungus. Several regional lists call it Least Concern. Some regional lists leave it unlisted. Numbers, however, appear stable.

Dead wood is abundant. Forestry removes stumps, though. Tidy woodland loses some habitat. Old orchards are vanishing.

Air pollution once hit it hard in Europe. Because the fungus also lives in parks and hedgerows, it faces no clear threat at present anywhere in its range.

Side by side

How It Compares

Common misreadings

What People Get Wrong

• This fungus is edible. The flesh is far too tough to chew.
• A black mark means the fungus is rotten. The colour change is a chemical reaction.
• This fungus grows only on dead wood. Living trunks and orchard trees also suffer.

Going further

Sources and Further Reading

• MycoBank, fungal nomenclature database
• Wikipedia, Bjerkandera adusta
• Ryvarden, L. and Gilbertson, R. L. 1993. European Polypores. Fungiflora.
• Willdenow, C. L. 1787. Florae Berolinensis Prodromus.

Quick hits

Five things to remember

• The pore surface blackens when scratched.
• Shelves can fuse into a crust 30 cm wide.
• Its enzymes break down industrial dyes.
• Mushroom farms treat it as a weed.
• Spores can irritate the lungs.