About Agaricomycetes
Agaricomycetes is a class of fungi belonging to the division Basidiomycota. Its classification is roughly the same as the Homobasidiomycetes (alternatively called holobasidiomycetes) defined by Hibbett & Thorn, with the addition of the orders Auriculariales and Sebacinales. This class includes not just mushroom-forming fungi, but also most species that were previously placed in the now-deprecated taxa Gasteromycetes and Homobasidiomycetes. Within the subdivision Agaricomycotina, which already excludes smut and rust fungi, Agaricomycetes are further distinguished by excluding the classes Tremellomycetes and Dacrymycetes, which are generally recognized as jelly fungi. Even so, a small number of former "jelly fungi" such as Auricularia are classified within Agaricomycetes. A 2008 estimate puts Agaricomycetes at 17 orders, 100 families, 1147 genera, and around 21000 total species. Modern molecular phylogenetic analyses have since been used to define several new orders within Agaricomycetes: Amylocorticiales, Jaapiales, Stereopsidales, and Lepidostromatales. In terms of ecology, nearly all Agaricomycetes species are terrestrial, with only a small number being aquatic. They grow in a very wide range of environments, and most act as organic decayers, especially of wood. Some species are pathogenic or parasitic, while others form mutualistic symbiotic relationships; these include the ecologically important ectomycorrhizal symbionts that associate with forest trees. General discussion of the morphological forms and life cycles of these fungi can be found in the article on mushrooms, in treatments of each individual order (linked in the table at right), and in species-specific accounts.
