The Collaborative International Dictionary
Polyporus betulinus
Polyporus \Po*lyp"o*rus\, n.; pl. Polypori. [NL., fr. Gr. poly`s many + ? a pore.] (Bot.) A genus of fungi having the under surface full of minute pores; also, any fungus of this genus.
Note: Polyporus fomentarius was formerly dried and cut in slices for tinder, called amadou. Polyporus betulinus is common in America, and forms very large thick white semicircular excrescences on birch trees. Several species of Polyporous are considered edible.