AUTOBASIDIOMYCETES 



463 



Polyporus borealis (Wahl.) Fr. is a characteristic and destructive 

 disease of the spruce in Europe, and it occurs on a variety of conifers 

 in America. 1 The bracketed sporophores are clustered, as shown 

 in Fig. 228. They are fleshy for some time, but finally tough and 

 dry. The spores are minute, measuring 4-5 x 3 /u. The mycelium 

 develops abundantly in the wood with typical markings (Fig. 229). 



FIG. 229. POLYPORUS. BOREALIS: LONGITUDINAL SECTION OF LOG, 

 SHOWING MYCELIUM. (Photograph by Geo. F. Atkinson) 



Polyporus carneus Nees causes 'a red rot, or peckiness, in the 

 common red cedar (Juniperus virginiand) and in the southern red 

 cedar (Jimiperus barbadensis\ as well as in other conifers. 2 



Polyporus Juniperinus von Schrenk is apparently the cause of 

 the white rot of the red cedar. 2 



Polyporus Schweinitzii Fr. is abundant in Europe on the Scotch 

 pine, Weymouth pine, and the larch. 3 This species is yellowish 



1 Atkinson, Geo. F. Cornell Agl. Exp. Sta. Built. 193 : 202-208. 1901. 



2 Schrenk, H. von. Div. Veg. Phys. and Path., U. S. Dept. Agl. Built. 21 : 1-22. 

 ph. 7-7. 1900. 



8 Schrenk, H. von. Div. Veg. Phys. and Path., U. S. Dept. Agl. Built. 25 : 18-24. 



