artist's bracket

Description

Artist's bracket is a large, hard, perennial fungus shaped like a shelf or hoof, growing sideways out of a tree trunk. The upper surface is reddish-brown to greyish-brown, undulating, with distinct concentric bands, often dusted with rusty-brown spore powder. The margin is white, and the underside is also white and turns brown when touched or scratched.

It grows all year round on living and dead trees, most often broadleaved ones (beeches, poplars, maples, horse chestnuts), in forests, parks and along roads. In Poland it is very common. A scratch on the white underside leaves a permanent brown mark, which is why the fungus is sometimes used for drawing.

It can be told apart from similar Ganoderma species by its zoned, matt or slightly shiny cap without a varnished coating and by its white margin. Reliable identification of the species within the genus can be difficult, but all of these fungi are inedible.

Identification features

Cap

Perennial fruiting body, hoof-shaped or semicircular, attached sideways, hard as wood or leather; width 10–50 cm (exceptionally up to 75 cm), thickness 1–5 cm, up to 10 cm according to some descriptions. Upper surface reddish-brown to brownish-grey, covered with a hard crust, strongly zoned (the concentric bands correspond to successive years of growth), undulating and bumpy, smooth or slightly shiny, without a varnished coating. Often covered with a thick, rusty-brown layer of settled spores. Margin pure white, bumpy, flattened.

Hymenophore (underside of the cap)

Tubes 4–12 mm long, arranged in several layers separated by a thin brown intermediate layer (one layer for each growing season). Pores round, small (about 4–6 per mm), white, turning brown when pressed or scratched. The hymenophore is not decurrent onto the stem, because there is no stem.

Stem

Absent; the fruiting body is sessile, attached sideways to the substrate by a broad base.

Flesh

Fairly soft, elastic to corky, whitish in young fruiting bodies, later cinnamon-brown to dark brown. Darkens when pressed, turns black with KOH. Taste bitter, slightly acrid. The flesh should not be tasted.

Spore print and spores

Spore print rusty-brown. Spores ovoid or ovoid-globose, warty; the reported dimensions are about 9 × 4.5–6.5 µm (uncertain data). They are produced in enormous quantities: from a 10 × 10 cm piece of hymenophore, as many as several billion spores can be released in a day.

Habitat and distribution

Ecology. Parasite and wood saprotroph, causing white rot; in an advanced stage the wood becomes bleached, spongy and interspersed with black zones. Grows on living trees (especially older, weakened ones), but more often on dead trunks and stumps. Mainly on broadleaved trees: beech, poplars, maples, horse chestnut, alder, birch, hornbeam, oaks, ash, linden, elm, willow, black locust; very rarely on conifers (fir, spruce, pine, and also cultivated Lawson's cypress and arborvitae). The fruiting bodies are sometimes colonised by insect larvae, including the fly Agathomyia wankowiczii (which forms characteristic urn-shaped galls on the pores) and the beetle Bolitotherus cornutus.

Distribution. Cosmopolitan species, found on all continents except Antarctica and on many islands. Very common in Poland, apart from higher mountain elevations: in forests, thickets, parks and along roads. Not legally protected in Poland.

Fruiting. The fruiting bodies are perennial and visible all year round; spores are released mainly from June to October.

What can it be confused with?

• Ganoderma adspersum (European artist's bracket) — Thicker fruiting body, darker, reddish flesh and larger spores; resistant to feeding by insect larvae.
• Ganoderma pfeifferi (beeswax bracket) — Hoof-shaped fruiting body (sometimes flat), not zoned; grows on beech.
• Ganoderma lucidum (reishi) — Cap covered with a varnished, shiny coating, usually on a lateral stem.
• Fomitopsis pinicola (red-belted conk) — Pale spore print, pale pores and cream-coloured flesh; often with a reddish zone near the cap margin.

Never rely on a single feature. If you are not sure — do not pick it; show the mushroom to a qualified mushroom expert.

Interesting facts

• The English name "artist's bracket" comes from the fact that scratching the fresh white underside exposes dark brown tissue, and the resulting drawing becomes permanent once the fungus dries.
• The age of a fruiting body can be estimated by counting the tube layers in a cross-section or the bands on the surface, much like the rings of a tree.
• From a 10 × 10 cm piece of hymenophore, as many as about 4.65 billion spores can be released in a day.
• Galls of the fly Agathomyia wankowiczii often occur on the pores; it is associated mainly with this fungus.