Cap: 4-12 cm across, hemispherical when young, later plane and pulvinate, somewhat campanulate, smooth to wrinkled surface, also aerolate, dull, finely tomentose, light brown to porphyry brown, sometimes also with yellowish or olive tints, margin thickly rounded.
Hymenophore: first whitish, later gray yellowish, turning black when touched, distinctly to strongly notched at the stipe.
Spore print: light brown
Spore: fusiform, (13)13,9-18,5(18,9) x 4,5-5,5(6) μm
Stem: 7-16 x 0,8-2,5 cm, usually ventricose, later cylindric longitudinally fibrillose-ribbed, covered with gray-blackish scabers, which disappear toward the apex, light yellow-brownish when young, later darker brown to gray-brown, solid, corticate, flesh longitudinally fibrous, tough, turning violet-blackish when cut, sometimes with greenish tints in the base.
Flesh: whitish, quickly turning reddish when cut, later changing to violet-blackish, thin, spongy, odor faint and pleasant, taste mild.
Habitat: under hardwoods by hornbeam, grows from summer to fall.