Russula firmula
Exemplar in Bavaria, Germany
Scientific classification
Domain:	Eukaryota
Kingdom:	Fungi
Division:	Basidiomycota
Class:	Agaricomycetes
Order:	Russulales
Family:	Russulaceae
Genus:	Russula
Species:	R. firmula
Binomial name
Russula firmula Jul. Schäff.
Distribution of Russula firmula in Europe and Asia

Russula firmula Mycological characteristics
	Gills on hymenium
	Stipe is bare
	Spore print is yellow
	Ecology is mycorrhizal
	Edibility is unknown

Russula firmula is a species of mushroom found in Europe and parts of Asia that has dark red-purple to red-brown cap. It is one of about 750 species in the genus Russula, which is distributed worldwide. Together with R. rubra, R. rutila and R. veternos, it was placed in the Rubrinae clade in 2017. ^[1]

Russula firmula has a yellow spore print. Its spores measure about 8.4 by 7 μm and have .8-1.2 μm high spines. Its pileocystidia measure around 72.5 by 10.3 μm. There are incrustations on its pileocystidia which stain bright pink after about 30 minutes in sulphovanillin, in contrast with the rest of the pileocystidia which stain black. The terminal cells at the cap margins are cylindrical, though tapered narrowly at one end. The basidia are around 46 by 12.8 μm. ^[1]

It is ectomycorrhizal with conifers, particularly spruce trees. It has a bitter taste.^[1]