Devil's Urn

Devil's Urn is one of the earliest woodland fungi of the year, pushing up through leaf litter while the trees are still bare. It begins as a closed, dark brown, club- or urn-shaped body which splits open at the top into a deep goblet with a toothed or ragged rim, sitting on a tough blackish stalk that runs down to a wiry black cord of mycelium.

The genus Urnula sits in the Sarcosomataceae, a family of dark, tough-fleshed cup fungi in the Pezizales. Its members share a leathery to rubbery texture, dark pigmentation and a habit of fruiting from buried woody debris, characteristics that set them apart from the softer, brighter Peziza relatives.

What makes it distinctive is the combination of size and season: a fruiting body up to 10 cm tall, almost black, standing among last year's leaves in March or April, when almost nothing else of that scale is fruiting.

Fruiting body

Initially a closed, elongated urn or club 2–5 cm tall, dark brown to nearly black and covered in fine scurfy fibrils. As it matures the apex tears open, and the body expands into a deep cup or goblet 3–8 cm across and up to 10 cm tall overall. The mouth is often distinctly ragged, splitting into irregular teeth or lobes that curl slightly outward.

Inner and outer surfaces

The inner (fertile) surface is smooth, matt and dark grey-brown to almost black, sometimes with a faint purplish tone. The outer surface is dull blackish brown, roughened and covered in minute scurfy or granular fibrils, particularly towards the base.

Stipe

A distinct, tough, blackish stalk 1–4 cm long tapers downward and continues into the substrate, where it is attached to a black mycelial cord and a buried stick or root fragment. Excavating carefully to expose that buried wood attachment is a useful confirmation.

Flesh and spore print

The flesh is thick, tough, leathery to rubbery and does not snap cleanly; it is blackish in the outer layers and paler grey within, with no colour change on cutting. Spores are colourless, elliptical and large; a deposit appears whitish, and mature urns will puff a visible cloud of spores when jarred.

Devil's Urn fruits from buried or partly buried hardwood — most characteristically fallen oak sticks and branch fragments, but also hickory, beech, maple, hornbeam and other broadleaves. Because the wood is often completely hidden under leaf litter, the urns can appear to be growing from bare soil until the stalk is traced downward.

The season is short and early: late winter through spring, typically March to May in temperate zones, sometimes overlapping with the first morels. Its stronghold is eastern North America, where it is common in oak-rich deciduous woodland, and it is also recorded in parts of Europe and Asia, though far less frequently.

Urnula craterium is saprotrophic on fallen hardwood, particularly small-diameter branch wood lying in contact with the soil. It has also long been linked to Strumella canker of oak, a canker disease whose asexual stage corresponds to this fungus, so the same organism may function both as a weak parasite on living or stressed trees and as a decomposer of the resulting dead wood.

The fungus overwinters as mycelium and black rhizomorph-like cords in the wood, then invests in a single tough fruiting body that can survive frost, wind and drying while the spring canopy is still open. Spores are discharged forcibly from operculate asci; the deep cup shape helps to funnel and protect the fertile surface until conditions favour release.

Urnula hiemalis and the related Plectania species are similar dark spring cups but are generally smaller, more regularly cup-shaped and lack the pronounced ragged, toothed mouth of a mature Devil's Urn. Plectania melastoma has orange-red granules on its outer surface, and Plectania nannfeldtii has a long slender black stalk and grows near melting snow with conifers.

The Black Bulgar (Bulgaria inquinans) is superficially similar in colour but is a stalkless, top-shaped rubbery button sitting directly on standing or fallen oak bark, not a stalked goblet on buried sticks. Old, blackened Peziza cups are thinner-fleshed, brittle rather than leathery and lack the black rooting stalk and mycelial cord.