Heterobasidion annosum (Fr.) Bref. syn. Fomes annosus (Fr.) Cke.
Wurzelschwamm Polypore du rond des pins, Root Rot Fruit body variable in shape, frequently forming large resupinate patches or irregular knobbly brackets 5–30cm across, 3–15cm wide, 1–2cm thick; upper surface uneven and lumpy covered in a light brown crust which darkens with age; margin thin, acute, white. Flesh whitish to pale wood-coloured. Smell strongly fungusy. Tubes 2–5mm long in each annual layer. Pores 2–4per mm, varying from circular to angular or irregularly elongated, white browning with age. Spores white, ovate, 4.5–6 x 3.5–4.5um. Hyphal structure dimitic; generative hyphae without clamp connections. Habitat parasitic on the roots of coniferous trees causing intensive rot and ultimately death of the infected tree; occasionally also infecting deciduous trees. Season all year, perennial. Common causing serious economical losses of conifers. Not edible. Distribution, America and Europe.