It forms mycorrhizal relationships with fungi of the genus Russula.
A variation on this staining method is used in mycology to differentially stain acid-fast incrustations in the cuticular hyphae of certain species of fungi in the genus Russula.
Russula nigricans, the blackening brittlegill or blackening russula, a gilled mushroom species found in woodland in Europe
To add to the confusion, Rolf Singer and later Robert Kühner and Henri Romagnesi described other species they named Russula delica.