Inonotus nidus-pici - Annual mushroom, very unstable, after ripening is quickly destroyed by larvae. Rust-colored with a pale olive edge, when dry, it acquires a dirty rust-brown color. The sporocarps line the hollow walls, covering them with a layer of barren mycelium, at the edges (usually in the upper part of the vault) they produce a tubular hymenophore, which is often nodular-wavy. Placenta in youth with a waxy-mucoid consistency.
Tubes 10 to 15 mm long, rust-brown after drying. Usually with a dozen lighter and darker vertical stripes, probably resulting from changes in the growth rate depending on weather conditions. Blades of tubes quite thick and smooth, dry dirty-dark-brown.
Usually circular pores, 0.08 to 0.12 mm in diameter.
Occurrence: On live or dying trunks of deciduous trees, usually oak, also beech. In hollows usually carved out by woodpeckers. Very rarely seen. The species not listed in Poland until 1965.
Value: Inedible mushroom.