Birch polypore or Artist's bracket

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.

Fruiting body 10-50 cm across (sometimes up to 70 cm), flat and spreading, fan-shaped or semicircular, attached sideways to the substrate (the trunk of a broadleaf tree). No stem. The upper surface is hard and corky, with clear concentric zones of annual growth, each zone marking a separate year of life. Color brownish gray, olive gray, with a rusty coating of spores in mature specimens. The margin is whitish when young and darkens with age.

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.

Tubular hymenophore — tiny white pores on the underside (4-6 pores/mm). Color whitish cream, turns distinctly dark when pressed or scratched — a key diagnostic feature. Spore print rusty brown (often visible as a rusty coating around the fruiting body on the trunk).

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. The fruiting body is attached to the substrate by its side edge.

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, brownish chestnut, leathery and hard as wood. Not usable in cooking. Faint woody smell.

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.

Faintly woody, nothing distinctive.