POLTPORACEAE 



493 



Fig. 164. Polyporales, Family Polyporaceae. Ganoderma applanatum (Pers. ex Fr.) 

 Pat. Vertical section through three-year-old sporophore. (Courtesy, Buller: Researches 

 on Fungi, London, Longmans, Green and Co.) 



30 or more cm. in height. Phellinus igniarius (L. ex Fr.) Quel, resembles 

 somewhat Fomes fomentarius but lacks the horny crust and is pubescent 

 when young. The hymenium of the pores has numerous sharp brown 

 spines. Ganoderma differs from the preceding genera in possessing spores 

 truncated at one end and two-layered, the brown endospore being spiny, 

 the spines projecting up into the hyaline exospore. The surface of the 

 spore fruit has a hard crust formed by a palisade of thick-walled elongated 

 cells. A stipe may be present in some species. A varnish-like coating may 

 be present over the whole surface or only on the stipe or may be entirely 

 lacking. In the narrow use of this name only those with the varnished 

 layer would properly belong to the genus. G. lucidum (Leyss. ex Fr.) 

 Karst. occurs on coniferous and deciduous trees and is annual. It is 

 varnished over the whole top surface as well as the stipe. G. curtisii 

 (Berk.) Murr. is perennial and may produce several layers of pores. 

 It loses its laccate covering early. G. applanatum (Pers. ex Fr.) Pat. lacks 

 the laccate surface entirely but has a whitish to gray crust. It is one of 

 the commonest species in North America, being found on fallen trees 

 and old stumps of deciduous species almost everywhere. Its spore fruits 

 may attain a diameter of 75 cm. White (1920) estimated that a large 

 spore fruit of this species may liberate 30 billion spores a day for several 

 months attaining a total of 5500 billion spores for the season. Yet of all 

 this vast number of spores carried far and wide by the wind all but a very 

 few must perish. With so many spores in the air it is not to be wondered 

 at that the fungus is very common wherever a deciduous tree has died 

 or its trunk has fallen. This fungus does not attack healthy uninjured 

 trees. (Figs. 163, 164.) 



Probably closely related to the genera grouped about the genus 



