FRUIT BODY 2–6 (9) cm across, 1–4 cm tall, cushion-shaped, rarely top-shaped, occasionally irregularly lobed, lacking a stipe, or with a rhizoid tuft or pad. Surface dry, smooth, at times with adhering soil, often slightly tomentose to fibrillose when old. PERIDIUM thick, tough, leathery above, underside of fruit body thinner, often disappearing in age. Whitish to gray. GLEBA coarsely loculate, firm when young, soon powdery, with fibrous trama cords. Dark brownish black to black, mottled with whitish, gray to tan trama, completely black when mature. STIPE indistinct, with coarse rhizomorphic cords extending into ground. ODOR indistinct when young, sometimes foul in age. TASTE indistinct. MICROSCOPY: Spores (18) 23–27 x 12–16 (20) μm, ovoid, ellipsoid or irregular, smooth, thick- walled, brown in KOH. Basidia narrow clavate, hyaline, 2-spored. Cystidia absent. Glebal trama interwoven, hyaline in KOH. Peridium a compacted trichoder- mium, composed of hyaline, interwoven, thin-walled hyphae 5–7 μm wide. Clamp connections absent.
ECOLOGY: Hypogeous to emergent in duff under conifers in high-elevation forest, especially under fir (Abies spp.) and pine (Pinus spp.). Fruiting in summer and early fall, fruit bodies may persist into late fall. Saprotrophic.
SIMILAR SPECIES: Some Elaphomyces species are superficially similar, but are typically smaller, round or nearly so, have a thick peridium around the entire fruiting body and a powdery spore mass when mature. Microscopically, Elapho- myces species are easily distinguished by the globose, spiny spores. Scleroderma polyrhizum has a thick peridium which splits at the top when mature, exposing a powdery spore mass; it lacks the cords through the gleba like Sedecula pulvinata, and has a thick basal peridium. Microscopically, S. polyrhizum (and other Sclero- derma species) have globose, spiny spores, often with a reticulate ornamentation.