Birch polypore or Tinder fungus

The fruiting body is hoof-shaped or hemispherical, attached to the birch at the side. Size 5-20 cm across, 3-8 cm thick. The surface is smooth, pale cream to flesh-gray or light brown, often with a thin, papery crust that cracks with age. The margin is even and rounded, slightly curved downward in mature specimens.

The fruiting body is 5-50 cm across (sometimes up to 70+), hoof-shaped to semi-hoof-shaped, attached sideways to the substrate. No stem. The upper surface is hard and corky, with distinct concentric zones of annual growth, each zone marking a separate year of life. Color: gray-brown, gray, olive-gray; in old ones dark gray to blackish. Old fruiting bodies often have cracks in the crust.

Tubular hymenophore. Tubes short, 0.3-0.5 cm deep, with round or oval pores, 3-5 per millimeter. White to cream, turning yellowish or brownish as it dries. Does not separate easily from the flesh.

Tube layer — fine, pale gray-brown pores on the underside (3-4 pores/mm). Color: gray-brown to brown. Spore print: white to pale cream.

The stem is absent or very short and fused to the tree. The fruiting body attaches to the birch bark at its side through a knobby outgrowth.

No stem.

Flesh of young fruiting bodies is white, springy, fleshy and soft to the touch, with a characteristic “marshmallow-like” edge. With age it becomes corky, hard and light. Dried flesh resembles cork — historically it was used for razor strops, for carrying embers and for mounting surgical instruments.

Flesh: very tough, corky-fibrous, rusty brown, leathery, hard as wood. Useless in the kitchen. Smell: faint, neutral.

Odor faint, mushroomy; in fresh specimens slightly pleasant with a sourish note. The taste of the flesh is bitter and astringent, unpleasant, with a quinine-like aftertaste. This is one of the reasons the mushroom is inedible.

Faint and neutral, nothing distinctive.