Smoky Bracket

The Smoky Bracket (Bjerkandera adusta) is one of the most frequently encountered small polypores of temperate hardwood forests and urban parkland. Its Latin epithet adusta means scorched, and mature brackets really do look as though the underside has been passed through a flame while the top stayed pale.

The genus Bjerkandera contains only a couple of widespread species and is defined by soft, thin, annual fruit bodies whose white flesh is separated from a much darker grey tube layer by a thin black line. That two-tone cross-section is the fastest way to confirm the genus with a knife.

It is an extremely adaptable white-rot fungus, fruiting on everything from fallen beech branches in ancient woodland to the cut stumps of street trees, and it is often one of the first polypores a beginner learns to recognise reliably because the grey pore surface is so unlike anything else fruiting on the same logs.

Cap

Annual, thin and flexible, individual brackets 2-7 cm across and only 1-6 mm thick, usually fused into extensive overlapping tiers or spreading in effused-reflexed sheets over the underside of logs. The upper surface is pale buff to greyish white, finely downy when young and becoming smooth, faintly zoned and often wavy or lobed at the thin margin.

Pores

This is the diagnostic feature. The pore surface is smoke grey to ash grey when fresh, darkening to near black with age or where rubbed and bruised. Pores are very small and round, about 4-7 per millimetre, so the surface looks almost smooth to the naked eye. The tube layer is shallow, typically under 2 mm.

Flesh and spore print

The flesh is white to pale cream, soft and slightly leathery, and in vertical section it contrasts sharply with the dark grey tube layer beneath, the two separated by a thin black line. The spore print is white, which surprises many people given how dark the pore surface looks.

The Smoky Bracket fruits on dead hardwood of many kinds, with beech, oak, birch, ash, willow and maple all commonly used. It occurs on fallen logs, stumps, standing dead trunks, large branches on the ground and the dead parts of living trees, and it is equally at home in old woodland and in managed parks and gardens. It occasionally appears on conifer wood.

Distribution is essentially cosmopolitan across temperate regions, including all of Europe, North America and much of Asia. Fresh brackets are produced mainly from late summer into late autumn, although the tough thin fruit bodies persist in a faded, greyer form through winter.

Bjerkandera adusta is a white-rot saprotroph that degrades both lignin and cellulose in dead hardwood, reducing firm wood to a pale, soft, fibrous mass. It is an efficient early to mid-stage coloniser, often taking over surfaces already opened up by other fungi and competing vigorously along visible dark demarcation lines where two mycelial colonies meet, a phenomenon that produces the black zone lines seen in spalted wood.

Because it tolerates a wide range of substrates and moisture conditions, it plays an outsized part in returning fallen hardwood to the soil in disturbed and urban habitats. It also occasionally colonises the wounds of living trees, spreading in already dead heartwood without functioning as a true parasite.

The Big Smoky Bracket (Bjerkandera fumosa) is closely related and shares the internal black line, but forms noticeably thicker, larger brackets with a pale ochre to greyish buff pore surface rather than a dark smoke-grey one, and it favours ash and willow.

Turkey Tail (Trametes versicolor) grows in the same tiered fashion on the same logs but has a strongly zoned, velvety, multicoloured cap and a bright white pore surface that never turns grey. The Mossy Maze Polypore (Cerrena unicolor) also has the black line under a hairy cap, but its underside is maze-like to toothed and pale, not finely and evenly grey-pored. Thin resupinate crusts such as Antrodia species have white to cream pores and lack the pale-flesh-over-dark-tubes contrast in section.