Russula emetica, commonly known as the sickener, emetic russula, or vomiting russula, is a basidiomycete mushroom, and the type species of the genus Russula. It has a red, convex to flat cap up to in diameter, with a cuticle that can be peeled off almost to the centre. The gills are white to pale cream, and closely spaced. A smooth white stem measures up to long and thick. First described in 1774, the mushroom has a wide distribution in the Northern Hemisphere, where it grows on the ground in damp woodlands in a mycorrhizal association with conifers, especially pine. The mushroom's common names refer to the gastrointestinal distress they cause when consumed raw. The flesh is extremely peppery, but this offensive taste, along with its toxicity, can be removed by parboiling or pickling. Although it used to be widely eaten in Russia and eastern European countries, it is generally not recommended for consumption. There are many similar Russula species that have a red cap with white stem and gills, some of which can be reliably distinguished from R. emetica only by microscopic characteristics. Taxonomy Russula emetica was first officially described as Agaricus emeticus by Jacob Christian Schaeffer in 1774, in his series on fungi of Bavaria and the Palatinate, Fungorum qui in Bavaria et Palatinatu circa Ratisbonam nascuntur icones. Christian Hendrik Persoon placed it in its current genus Russula in 1796, where it remains. According to the nomenclatural database MycoBank, Agaricus russula is a synonym of R. emetica that was published by Giovanni Antonio Scopoli in 1772, two years earlier than Schaeffer's description. However, this name is unavailable as Persoon's name is sanctioned. Additional synonyms include Jean-Baptiste Lamarck's Amanita rubra (1783), and Augustin Pyramus de Candolle's subsequent new combination Agaricus ruber (1805). The specific epithet is derived from the Ancient Greek emetikos/εμετικος 'emetic' or 'vomit-inducing'. Similarly, its common names of sickener, emetic russula, and vomiting russula also refer to this attribute. Russula emetica is the type species of the genus Russula. According to Rolf Singer's infrageneric classification of Russula, it is also the type of the section Russula. In an alternative classification proposed by Henri Romagnesi, it is the type species of subsection Emeticinae. A molecular analysis of European Russula species determined that R. emetica groups in a clade with R. raoultii, R. betularum, and R. nana; a later analysis confirmed the close phylogenetic relationship between R. emetica and the