Description
Fruit-body of the imperfect form (anamorph) annual, bulbous, Ø 10-20 x 5-10 cm. Surface crumbly, hard, coarse, wart-like, black. Flesh charcoal-like, dark brown. Perfect form (teleomorph) crust-shaped, Ø several centimetres to some decimetres, 0,5-1 cm thick, young soft and corky, old brittle, hard. Tubes slanting, to 1 cm long. Pores angular to elongated, 3-5 per mm, young whitish, then brown, with sheeny reflection, old dark brown.
Spore-print colour olive-brown.
Occurrence
Underneath the bark of birches, ultimately breaking through the bark.
Parasitic.