490 



CLASS BASIDIOMYCETEAE 



Thelephoraceae and Clavariaceae because of the similarity of the struc- 

 ture of the spore fruit and spores to those famihes, in spite of the occur- 

 rence of the hymenium in pores. The genus Polyporus in the Hmited sense 

 consists of tough, fleshy, centrally or laterally stipitate forms. P. iuherasier 

 (Jacq.) Fr., considered by Donk and Singer to be the type species of the 

 genus, develops, underground, large, hard, sclerotium-like structures of 

 intermingled hyphae and particles of soil, called pietra fungaia in Italy. 

 When placed in a warm, moist situation several sporophores develop from 

 each sclerotium. These are centrally stipitate, with pileus somewhat 

 funnel-shaped at maturity, scaly, yellowish, with rather large pores. This 

 is fleshy when young and is prized for food by the Italians who collect 

 the sclerotia and preserve them for some time and grow from them the 

 edible spore fruits. Closely related is P. squamosus (Huds.) Fr. (P. caudi- 

 cinus (Scop.) Murr.), which is very common and destructive to many 

 kinds of deciduous trees. Its stipe is usually lateral or eccentric and the 

 pileus may exceed a diameter of 50 cm. and a thickness of 3.5 cm. It 

 occurs in imbricated masses growing from the trunks of the infected 

 trees. It also is edible when young. Other fungi included in the old genus 

 Polyporus are the following: Laetiporus sulphureus (Bull, ex Fr.) Murr., 





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^Si*^" 



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Fig. 161. Polyporales, Family Polyporaceae. Grifola berkeleyi (Fr.) Murr. (Courtesy, 



M. B. Walters.) 



