Pig's Ears

Pig's Ears is a robust spring ascomycete usually treated in the genus Gyromitra (long known as Discina perlata or Discina ancilis). Unlike the brain-shaped members of the genus, it keeps a broadly cup-like or saucer-like form throughout its life, and the folds that give it character develop on the inner, spore-bearing surface rather than over an inflated head.

The fungus belongs to the Discinaceae, a family of large, fleshy spring ascomycetes that includes the various false morels. Family traits visible in the field include a thick, brittle-fleshy fruiting body, a spore surface that is smooth in youth and becomes puckered with age, and a rudimentary stalk built of fused white ribs rather than a clean cylinder.

What makes it distinctive is the combination of size and posture. Mature fruit bodies can span the width of a hand, sit low and lopsided on their substrate like a folded ear, and show a strong colour contrast between the dark reddish-brown fertile face and the pale buff, minutely roughened outer surface.

Fruiting body

Begins as a deep, thick-walled cup 2-6 cm across and expands to a shallow saucer or irregular ear-shaped disc 4-15 cm wide. The margin is often inrolled at first, then becomes wavy, split or lobed, and the whole structure frequently grows lopsided where it is pressed against wood.

Fertile (inner) surface

Dark reddish-brown, chestnut, or dull chocolate, smooth when young and developing coarse radiating wrinkles, veins and blister-like folds toward the centre as it matures. The surface is dry and slightly waxy in appearance rather than shining.

Outer surface and stalk

The underside is much paler - whitish, buff or pale tan - and finely scurfy, mealy or minutely warted. Beneath it sits a very short, stout, off-white stalk formed of thick folded ribs that flare outward into the cup; in many specimens the stalk is barely visible and the fruiting body appears to sit directly on the wood.

Flesh and spore print

The flesh is thick, pale, brittle and somewhat rubbery, showing no notable colour change when broken. The spore deposit is white to pale cream. Microscopically the spores are large, ornamented, and carry a pointed projection at each end, a feature that separates the discinoid fungi from ordinary cup fungi.

Pig's Ears is a wood-inhabiting species that fruits on well-rotted conifer logs, buried branches, sawdust, bark chips and the deep needle duff around old stumps. It has a strong preference for spruce, fir and pine debris and is most abundant in cool, moist coniferous forest.

Fruiting begins soon after snowmelt in montane and northern forests, running from early spring into early summer at higher elevations and later in the season as altitude increases. It is widespread across northern and montane North America and occurs across the boreal and montane zones of Europe and northern Asia.

This is a saprotrophic fungus that decays woody substrates, colonising conifer logs and buried wood in the later stages of decomposition when the timber is already soft and crumbling. Its mycelium ramifies through the sodden wood and the needle litter packed around it, breaking down residual cellulose and returning nutrients to the forest floor.

Fruiting is tied tightly to spring moisture and rising soil temperature. Ascospores are shot from the exposed inner surface of the cup, often in visible puffs when the fruiting body is jarred, and are dispersed by air currents to fresh woody debris. Because it needs wood that is already well decayed, colonies often reappear on the same log or stump for several successive years until the substrate is exhausted.

Gyromitra ancilis and other regional discinas are extremely close in appearance and are separated mainly by spore ornamentation and by substrate preference; many field guides treat them as a single variable complex. Gyromitra infula, the hooded false morel, differs sharply in shape: its fertile surface is carried on a saddle-shaped, two- or three-lobed head raised on an obvious stalk, rather than spread over an open saucer.

Peziza badia and other large brown cup fungi grow on soil rather than wood, lack the thick ribbed stalk base, and have thinner, more brittle flesh with a smoother inner face that does not develop the coarse central veining. Gomphus clavatus, which shares the name pig's ear in some regions, is an entirely different basidiomycete with a vase-shaped violet-tinged body and wrinkled, decurrent ridges running down the outside, not a flat brown disc.