Russula nigricans
English: Blackening brittlegill; Blackening russula; Thick-leaved black bolete.
German:
Synonym: Agaricus nigricans.
Name: the Latin nigricans means blackening.
Region: Britain, Northern Europe, East Coast of North America.
Habitat: deciduous and coniferous woodland.
Mycology
Appearance: late summer and autumn, first year white, second year black.
Cap: dirty white when young, but swiftly turns brown, and then black on ageing; 5 to 20 cm in diameter; large depression in the centre; three quarter peeling; flesh has a fruity smell; when cut turns pale Indian red, and then grey, and black within 20 minutes.
Stype: stem is white, firm; straight; 5 to 8 cm long, 2 to 5 cm wide; also blackens with age.
Hymenium: gills off-white initially, very widely spaced, and are adnate; turn red, then grey, finally black, when bruised.
Spore print: white.
Spores: warty; oval; ± 7 by 7 μm.
Ecology: sometimes parasitised by Asterophora or Nyctalis.
Taxonomy
It is placed in the Compactae group, subsection Nigricantinae.
Similar species, that also bruise red then black include Russula acrifolia and Russula dissimulans.
Russula albonigra has closer gills and is far less common. It bruises directly to black, lacking the red intermediary phase.