Blackening brittlegill

Caps of Russula nigricans are 6 to 20 cm in diameter, convex with an inrolled margin and then later flatter and centrally depressed, the caps are dirty white at first, turning grey-brown and then eventually blackening all over. The sometimes finely felty but often smooth cap peels to about 75%. Below the cap cuticle, which often cracks in dry weather, the flesh is white, greying with age. The widely-spaced adnate gills of Russula nigricans are thick and extremely brittle, they are interspersed with many shorter gills known as lamellae. Ivory-white to straw-coloured at first, the gills soon turn grey and bruise rosy red-brown when damaged. Eventually, like the rest of the fruiting body, the gills turn dull black. The smooth, blackening stems are cylindrical or taper in slightly towards the base, 1 to 4 cm in diameter and 3 to 8 cm tall. The stem flesh is white at first, reddering and then blackening with age or when bruised. There is no stem ring.