Porphyrellus porphyrosporus - Cap diameter 50 to 160 mm, hemispherical, later convex, cushion. Dry, smooth, suede, felt, cracked surface in old age. At first light gray, then gray-brown, olive-brown, red-brown, even black-brown; uncollectible skin.
Tubes up to 25 mm long, adnate to the stipe or slightly cut out, first gray-white, gray-yellow, later gray-brown; darken when damaged.
Small pores, up to 1 mm in diameter, initially white-gray, later gray-brown; when damaged, they turn green, then red and black.
Stem 40 to 160 mm high, 10 to 40 mm thick, barrel-like, cylindrical; suede surface, wrinkled, longitudinally fibrillose; bottom dirty-white, higher gray-brown, hat-like or even black, without a mesh.
White, yellowish flesh greening, bruising or pinking at the intersection. Initially quite firm, then soft, wadded, thick up to 20 mm in a hat. Aroma sour, earthy, taste mild, sour, slightly spicy, rather unpleasant.
Occurrence: On the ground, in deciduous, mixed and coniferous forests, especially piedmont and mountain; uncommon, grows individually or in small groups from July to October.
Value: Inedible mushroom.