Phaeolus schweinitzii (Fr.) Pat. syn. Polyporus schweinitzii Fr. Fruit body sometimes forming amorphous cushions, more often subcircular, 10–30cm across with a short thick stalk, soft and spongy when fresh drying fragile and light; upper surface concave, rough, hairy, concentrically grooved at first, dark sulphur-yellow becoming rusty or dark brown and finally blackish with age. Stem brown, very short and thick, merging into the cap and covered in tubes. Flesh rusty brown, fibrous. Tubes 3–6mm long, decurrent, concolorous with the upper surface. Pores 0.3–2.5mm across, circular, angular or irregular, yellow, olivaceous or tinged rust, finally maroon brown, often glistening in the light. Spores whitish tinged yellowish, ovate to elliptic, 5.5–7.5 x 3.5–4um. Hyphal structure monomitic; generative hyphae lacking clamps. Habitat parasitic on conifers, usually arising from the roots. Season autumn. Occasional. Not edible. Distribution, America and Europe.