Shade Tree and Timber Destroying Fungi. 



227 



the surface of the wood in thin smooth patches, or some forms are 

 shelving, when the under side is smooth and is the fruiting surface. 

 These belong to the family Tlieleplioraceoi. A few of its members 

 are very destructive to wood and some are parasites on trees. In 

 another family the members are known as " coral fungi," or " fairy 

 clubs" a large number of them belonging to the well known genus 

 Clavaria, from which the family name C lavariacecB is derived. 

 The fruiting surface is distributed all over the surface of the plant. 

 To a third family, Jlydnacece, belong the " hedgehog fungi," with the 

 fruiting surface on spines, 

 a few species of whicli are 

 well known. A number 

 of the members of the two 

 last named families grow 

 on wood, but often appear 

 in late stages of decay. A 

 few species like Ilydnum 

 septentrionale on maple, 

 and II. schiedei'mayeri on 

 apple, are destructive. 



The two largest families 

 are known as the Agari- 

 cacece, to which the com- 

 mon mushroom belongs, 

 and the Polyporacem. In 

 the latter the fruiting sur- 

 face is in the form of a honey-comb on the under side of the fruit 

 body. It is to this last named family that the species belong which 

 are treated of here. 



The gross characters, those which are quite easily made out with- 

 out the aid of a microscope, are chiefly the ones presented here, 

 since a detailed account of microscopic structures and changes 

 brought about in the wood by the action of the fungus, are rather 

 too technical for full treatment in this paper. 



POLYPORUS BoREALIS. ■ 



Polyportos horecdis occurs on pines, spruces, the hemlock, etc., 

 and is widely distributed over the North Temperate Zone. It 



57. — Polyporus borealis, section of fruit body. 



