Native Bread

Native Bread is unusual among polypores in that its most conspicuous structure is not the mushroom at all but the sclerotium — a hard, rounded, subterranean mass of compacted mycelium and mineral matter that can reach the size of a football. Broken open it is white and marbled with translucent lines, and it was this bread-like appearance that gave the fungus its common names.

The fruitbody itself is comparatively modest: a stalked, tan to brown, funnel-shaped cap with a white pored underside, emerging on a tough stem that traces back down to the buried sclerotium. Placing it in Laccocephalum (family Polyporaceae) recognises a small group of Australian stalked polypores that all form sclerotia; the species was long known as Polyporus mylittae.

The sclerotium is a survival and storage device. It allows the fungus to sit dormant in dry sclerophyll country through long rainless spells and even through fire, then draw on its reserves to push up fruitbodies when conditions turn favourable — which is why the species is so often reported from recently burned ground.

Sclerotium

Rounded to irregularly lobed, 5-30 cm across and hard enough to resist a knife, with a thin dark brown to black rind. The interior is white to cream, dense, and marked with translucent, gelatinous-looking veins that give a marbled or bread-crumb pattern. It is found buried in soil or embedded in decaying wood, usually a few centimetres to tens of centimetres down.

Cap

The fruitbody cap is 3-10 cm across, circular, convex at first and soon shallowly to deeply depressed or funnel-shaped, coloured pale tan, ochre, cinnamon or greyish brown, with a dry, smooth to finely scurfy surface and an inrolled then wavy margin.

Pores

The underside carries a poroid surface, white to cream, ageing buff, with small angular to roundish pores. The tube layer is shallow and runs down the stipe (decurrent) in most specimens, and the pore mouths may become slightly toothed or lacerated in age.

Stipe & flesh

The stipe is central to slightly off-centre, 2-8 cm long, tough, fibrous, pale to brownish and often darker toward the base, and continues into the sclerotium below. Flesh is white, tough and leathery, unchanging when cut. The spore print is white, and spores are smooth, hyaline and cylindrical to elliptical.

Native Bread is a fungus of dry sclerophyll forest and woodland dominated by eucalypts, and is also recorded from wetter forest margins. The sclerotium develops in soil or in buried decaying eucalypt wood, so fruitbodies typically emerge from bare ground, from beneath logs or from among litter with no obvious wood visible at the surface.

The species is Australian, recorded widely across the southeast including Victoria, New South Wales, South Australia and Tasmania, with related Laccocephalum species elsewhere on the continent. Fruiting is concentrated in the cooler, wetter months from autumn into winter, and it is frequently reported in the season following a bushfire, when the sclerotium's stored reserves let it fruit on ground where competitors have been cleared away.

The fungus is saprotrophic, causing a white rot in buried eucalypt wood and woody debris by degrading lignin along with cellulose, and thereby returning carbon and minerals to the forest soil. The sclerotium represents accumulated reserves of that decay activity, packaged into a compact, rind-protected mass that can survive drought, heat and fire.

When rain and cool temperatures arrive, the sclerotium mobilises those reserves to produce one or more stalked fruitbodies at the soil surface, drop a white spore load, and then resume dormancy or exhaust itself. This boom-and-wait life cycle, controlled by a long-lived storage organ, is shared with a handful of other sclerotium-forming polypores worldwide and suits the erratic rainfall of Australian sclerophyll country particularly well.

Other Laccocephalum species are the closest matches. Laccocephalum basilapiloides and Laccocephalum tumulosum also produce stalked caps from sclerotia but differ in cap size and colour, pore dimensions and the size and shape of the underground mass; excavating the base is usually necessary to separate them confidently.

Polyporus arcularius and Polyporus brumalis are stalked polypores of similar stature but grow directly from dead wood with no sclerotium, and P. arcularius has conspicuously large, elongated hexagonal pores and a hairy cap margin. Wolfiporia extensa forms a comparable hard sclerotium but occurs in the northern hemisphere and Asia and produces a flat, resupinate pore surface rather than a stalked cap. Pisolithus fruitbodies can also be dug up as hard masses but are stalkless puffball-like bodies whose interior consists of pea-like chambers that break down into powder.