Kingdom: Fungi
Phylum: Basidiomycota
Class: Basidiomycetes
Order: Polyporales
Family: Polyporaceae
Genus: Polyporus

From The Polyporaceae of North America
By William A. Murrill

This species was described by Batsch as follows: “Stipitatus; stipite subgracili, subclavato; pileo membranaceo convexo, subulato-fimbriato; stipiteque concoloribus, spadiceo-rufis; cellulis latissimis, rhombeis, aequalibus albis.” Fries placed it in the genus Favolus, which he treated as a subgenus under Polyporus. Its tubes are certainly favoloid, but its close relationship to P. Polyporus has kept it near this species rather than with species of Favolus. Wright’s specimen of P. lentus from Connecticut seems nothing more than P. arcularius. There is at Kew also the remains of a specimen from Ohio, which very probably belonged in the same category.

P. arcularius shows little variation except in size throughout its wide range. It occurs on decaying wood and shows much the same habit as P. elegans and P. Polyporus, but differs from these species in occurring more abundantly in the south.