Russulaceae Lotsy 1907.
The Russulaceae are a diverse family of fungi in the order Russulales, comprising one of the most species-diverse lineages of ectomycorrhizal fungi with an estimated number of some 2000 accepted species (Kirk, 2017) and worldwide distribution. The genera of this family containing mostly agaricoid forms (gilled mushrooms) including Lactarius, Lactifluus, Multifurca, and Russula. The agaricoid genera are distinguished from other gilled mushrooms by the consistency of the brittle flesh of their fruitbodies, which is granular, and breaks easily, somewhat like a piece of chalk (Lotsy 1907), never have a volva, but a partial veil can be found in some tropical species (Heim 1938, Singer et al. 1983). Gills are adnate to decurrent (Buyck et al. 2008). Pileus can be dull to very colourful, the latter especially in Russula (Courtecuisse 2013), concentrically ringed (zonate) caps occur in all Multifurca and several Lactarius species (Buyck et al. 2008, Courtecuisse 2013). A conspicuous feature of the "milk-caps" in Lactarius, Lactifluus, and Multifurca furcata is the latex or "milk" their fruitbodies exude when bruised (Buyck et al. 2008). These genera form a mutualistic ectomycorrhizal root symbiosis with trees and shrubs, which the important roles they play as plant root mutualists in ecosystem functioning, global carbon sequestration, and a potential role in technology development toward environmental sustainability. In addition to these typical agaricoid forms, the family contains the resupinate (crust-like)-forming genera including Boidinia, Gloeopeniophorella, and Pseudoxenasma. They develop crust-like fruitbodies with a smooth, porous, or flaky surface and grow on tree logs or dead branches (Hjortstam & Larsson 1976, Maekawa 1994, Larsson & Larsson 2003, Hjortstam & Ryvarden 2007). Altogether, the Russulaceae comprise around 2000 accepted species, Russula is by far the largest genus, followed by Lactarius, Lactifluus, Boidinia, Multifurca, Gloeopeniophorella, and Pseudoxenasma, respectively. The family Russulaceae includes a large number of edible species collected and consumed worldwide (Wang 2020), especially the species of Lactarius, Lactifluus and Russula. However, several species have a hot to very acrid taste and can cause gastrointestinal symptoms (Miller & Miller 2006), and some species are truly poisonous include Russula subnigricans causes rhabdomyolysis and is potentially lethal (Chen et al. 2014), and Lactarius turpis contains a mutagenic substance (Suortti et al. 1983).