is challenging, since the presence of host trees is required. In spite of this difficulty, the European Lactarius deliciosus has been successfully grown in "mushroom orchards" in New Zealand. Chemistry Fruitbodies of Russulaceae have been the subject of natural product research, and different classes of organic compounds have been isolated from them. Aroma compounds are responsible for the particular odour or taste in some species, e.g. sotolon in the fenugreek-smelling Lactarius helvus, or the similar quabalactone III in Lactarius rubidus which causes a maple syrup-like odour in dried specimens. Pigments have been isolated from brightly coloured species, e.g. (7-isopropenyl-4-methylazulen-1-yl)methyl stearate from the blue Lactarius indigo or russulaflavidin and a derivative from the yellow Russula flavida. Some Russula species contain pigmented pteridine derivatives called russupteridines that are not found in the milk-caps. Sesquiterpenes are characteristic secondary metabolites of many Russulaceae, especially milk-caps which have been quite intensively studied. They are thought to be responsible for the hot taste in many species and may have deterrent, antifeeding functions in nature. Other metabolites isolated from different species include dibenzonaphtyridinone alkaloids, prenylated phenols, benzofurans, chromenes, natural rubber (polyisoprene), sterols, and the sugar alcohol volemitol. Among toxic substances, Lactarius turpis contains the mutagenic alkaloid necatorin, and the small compound cycloprop-2-ene carboxylic acid has been identified as the toxic agent in Russula subnigricans. Some secondary metabolites showed antibiotic properties in laboratory tests. An ethanolic extract of Russula delica was antibacterial, and a lectin from Russula rosea showed antitumor activity. References External links Russulales News: Database, literature, identification Peat Bog and Mire Russulaceae Ghent University, Mycology: An integrated approach to the phylogeny and phylogeography of the Russulaceae (Basidiomycota) Russulales Basidiomycota families Taxa named by Johannes Paulus Lotsy Taxa described in 1907