Heterobasidion annosum

Heterobasidion annosum
Scientific classification
Kingdom:	Fungi
Division:	Basidiomycota
Class:	Agaricomycetes
Order:	Russulales
Family:	Bondarzewiaceae
Genus:	Heterobasidion
Species:	H. annosum
Binomial name
Heterobasidion annosum (Fr.) Bref. (1888)
Synonyms
Boletus annosus Boletus cryptarum Fomes annosus Fomes annosus f. cryptarum Fomes cryptarum Fomitopsis annosa Friesia annosa Heterobasidion annosum f. cryptarum Heterobasidion cryptarum Physisporus makraulos Placodes annosus Polyporus annosus Polyporus cryptarum Polyporus fuscus Polyporus irregularis Polyporus makraulos Polyporus marginatoides Polyporus scoticus Polyporus subpileatus Polystictoides fuscus Polystictus cryptarum Poria cryptarum Poria macraula Pycnoporus annosus Scindalma annosum Scindalma cryptarum Spiniger meineckellus Spongioides cryptarum Trametes annosa Trametes radiciperda Ungulina annosa Ungulina annosa f. cryptarum Ungulina annosa f. makraulos Heterobasidon irregulare

Heterobasidion annosum Mycological characteristics
	Pores on hymenium
	No distinct cap or offset
	Hymenium is decurrent
	Lacks a stipe or is bare
	Spore print is white
	Ecology is parasitic
	Edibility is inedible

Heterobasidion annosum is a basidiomycete fungus in the family Bondarzewiaceae. It is considered to be the most economically important forest pathogen in the Northern Hemisphere. Heterobasidion annosum is widespread in forests in the United States and is responsible for the loss of one billion U.S. dollars annually. This fungus has been known by many different names. First described by Fries in 1821, it was known by the name Polyporus annosum. Later, it was found to be linked to conifer disease by Robert Hartig in 1874, and was renamed Fomes annosus by H. Karsten. Its current name of Heterobasidion annosum was given by Brefeld in 1888. Heterobasidion annosum causes one of the most destructive diseases of conifers.^[1] The disease caused by the fungus is named annosus root rot.