264 



Mycologia 



As mentioned above, these three species have usually been 

 grouped as a part of the genus Polypoms, or if given specific 

 rank, placed in the section with Fomes as an exception to the 

 perennial character. There is perhaps sufficient reason for giving 

 this group specific rank, for the red varnished pileus, and the 

 truncate, apparently echinulate spores are definite and fixed char- 

 acters. The spores are especially exceptional. They appear to 

 be echinulate, but closer examination shows, as Professor Atkin- 

 son pointed out, that the roughening is a sculpturing of the inner 

 side of the spore-wall and not the outer as in the first impression. 

 The species may be dscribed as follows : 



POLYPORUS TSUGAE (Murrill) OVERHOLTS^ 



Pileus reniform or flabelliform, short stipitate when attached 

 to trunks or stumps above ground level, longer stipitate when at- 

 tached to roots, 5-15X6-20X 1-4 cm., with a mahogany col- 

 ored or almost black, shining encrusted surface, glabrous, sulcate ; 

 context white or nearly so throughout, .5-2 cm. thick ; tubes .5-1 

 cm. long, mouths white or brown, averaging 4-6 per mm. ; stem 

 lateral with color and context as in pileus, 3-15 cm. long, 1-3 cm. 

 thick ; spores ovoid with a truncate base, apparently echinulate, 

 light -brown, 9-1 1 X 6-7 ; hyphae very irregular and much 

 branched up to 15 /x in diameter. 



On standing or prostrate trunks, stumps, or exposed or nearly 

 exposed roots of hemlock, Tsuga canadensis, probably with a 

 range of its hosts. Occasionally on pine. 



It has been reported from Vermont, New Hampshire, Massa- 

 chusetts, New York, New Jersey, Pennsylvania, Ohio, West Vir- 

 ginia, and North Carolina. 



The fungus is at first a sap-rot but it eventually destroys the 

 heart-wood also. Near New Brunswick, a partly uprooted and 

 leaning trunk 14 inches in diameter was entirely destroyed by 

 this rot. Few stumps or dead trunks escape its attacks when it is 

 present in a locality and since it is quite rapid in its work, it is a 

 potential source of danger to stored hemlock lumber. 



When first attacked, the wood turns a little darker in color and 

 becomes dull and porous looking like a piece of fine grained blot- 



2 Polyporaceae Middle-Western U. S., L. O. Overholts. Washington Uni- 

 versity Studies, Vol. Ill, part I, No. i. 1915. 



