Conifer Mazegill Identification Guide

The setting and first impression

The Conifer Mazegill is a fungus of exposed, sunlit, seasoned conifer wood, and the setting is often more built than wild. You meet it on the sawn end of a stacked spruce log, along the top rail of a pine fence, on a weathered bench, on the decking of a forest hide, on the cut face of a stump in a clearing, or on structural timber under a shed roof. In natural habitat it takes the sunny upper surfaces of fallen conifer trunks and standing dead snags, and it tolerates drought and full sun far better than most bracket fungi.

What you first see is a row of small, tough, rusty-brown fans, often dozens of them fused edge to edge into a continuous band that follows a crack or a sawn face. From the top they look zoned and hairy, and if the colony is actively growing there is a startlingly bright yellow-orange to rust-orange line along the outer rim. That bright growing margin against a dark, weathered interior is the first impression to hold on to.

Reading the upper surface

Take one bracket and work through its top.

Size and shape. Two to twelve centimetres wide, projecting one to eight centimetres from the wood, and rarely more than a centimetre thick. The outline is a semicircular fan or an elongated shelf, frequently irregular where neighbours have fused. Where it grows on a vertical face it forms proper brackets; on the flat top of a log it can spread out as an almost resupinate crust with a raised edge.

Texture. Coarsely hairy to shaggy in fresh growth, becoming matted and finally almost bald and rough in old weathered zones near the point of attachment.

Colour and zoning. Strongly zoned in concentric bands: rusty orange and yellow-brown at the margin, through tawny and chestnut, to dark brown or nearly black in the oldest inner zones. Old brackets that have sat through a winter fade toward grey-brown but usually keep some rust tone somewhere.

Attachment. Broadly attached to the wood, sessile, with no trace of a stipe.

The spore-bearing surface

Turn the bracket over. This is where Gloeophyllum sepiarium separates itself from almost every other tough bracket you will meet on conifer wood, because the underside is not poroid: it carries gills.

The hymenophore consists of thick, blunt, radiating plates running from the attachment point out to the margin. Near the margin they are reasonably regular, spaced fairly closely at roughly fifteen to twenty per centimetre, but toward the base they fork, join and cross-connect into an irregular maze, which is where the common name comes from. The gills are ochre to tan when young, darkening to a dull brown or dark brown with age, and they are tough and dry, not soft or waxy.

Press one with a fingernail. It will not tear or crumble like a soft gill; it flexes and springs back, because the entire fruit body is leathery.

Flesh, section and colour change

Cut through a bracket from margin to attachment with a strong blade; a hand lens helps here because everything is thin. The flesh is one to three millimetres thick, uniformly rust-brown to dark brown, and its texture is tough, corky-leathery and fibrous. You can bend a fresh specimen almost double without breaking it; a dried one snaps.

There is no colour change on cutting, no latex, no bruising and no colour shift on handling. If you carry chemicals, a drop of potassium hydroxide on the flesh darkens it immediately to blackish, which is consistent with a brown-flesh bracket and helps rule out the white-fleshed maze polypores.

Spore print

Prints from thin leathery brackets are awkward but perfectly possible from actively growing material with a bright margin. Cut a piece of the outer edge with the gill plates intact, prop it hymenium-down over dark paper on two matchsticks so the plates are not squashed, cover it with a container to keep humidity up, and leave it overnight in a still, cool place.

The deposit is whitish to pale cream and it is easiest to see on black card or on a glass slide held to the light. Do not expect a heavy print; older brackets that have already released their spore load may give nothing at all. Under a microscope the spores are colourless, smooth and cylindrical to slightly curved.

Substrate, season and ecology

Substrate is close to diagnostic in itself. This is a conifer specialist, strongly associated with spruce, pine, fir, larch and Douglas fir, and it is famous for colonising worked timber: fence posts and rails, log stacks, sawn ends, sleepers, bridge planking, decking and construction lumber. Occurrences on broadleaf wood exist but are the exception.

It is a brown-rot fungus. Its enzymes remove the cellulose from the wood and leave brown lignin behind, so infected timber becomes dry, brown and cracked into cubes that crumble in the fingers. Because of this, established colonies are frequently found on wood that is already visibly failing.

The fruit bodies are annual to weakly reviving and extremely durable. Fresh growth with a bright margin generally appears from late spring through autumn, but the tough weathered brackets persist all year, and a colony may add a new zone of growth on the same bracket in a following season. Sun exposure is not a limitation; some of the best colonies are on south-facing surfaces that dry completely between rains.

Separating it from look-alikes on morphology

Gloeophyllum abietinum. The closest relative. Its gill plates are markedly fewer and more widely spaced, roughly eight to twelve per centimetre at the margin, and the whole fungus is greyer and darker with a much less hairy upper surface and little or no bright orange growing edge.

Gloeophyllum trabeum. Also brown-fleshed and on conifer or worked wood, but its hymenophore is intermediate, made of elongated pores and short maze-like plates rather than clean radiating gills, and it is usually paler and thinner.

Gloeophyllum odoratum. Thick, lumpy and irregular rather than fan-shaped, bright ochre-yellow, with a poroid underside, growing on spruce stumps, and with a strong aniseed odour.

Lenzites betulina. Genuinely gilled and superficially similar, but grows on broadleaf wood, has a whitish to greyish hairy upper surface often greened by algae, whitish gill plates, and above all white flesh in section.

Daedaleopsis confragosa. On broadleaf wood, especially willow, with a smooth reddish-brown zoned cap, pale flesh, and elongated maze-like pores that discolour when rubbed.

Trametes species. Trametes versicolor and Trametes hirsuta have white flesh and true round pores, and their whitish undersides look nothing like brown radiating plates once you turn them over.

Trichaptum abietinum. Extremely common on the same conifer logs, but thin, small, greyish above and with a violet-tinted, toothed to irregularly poroid underside that fades to buff.

Neolentinus lepideus. Gilled and often on the same worked conifer timber, but it is a true stalked mushroom with a white scaly cap and white flesh, not a leathery bracket.

Field checklist

Conifer wood, often sawn or worked and often sun-exposed; small tough zoned hairy brown fans, frequently fused in rows; a bright orange growing margin when active; thick radiating gill plates that fork into a maze near the base; brown leathery flesh with no colour change; whitish spore print; brown cubical rot in the timber below.