72 Journal of Agricultural Research voi. iii. No. i 



DESCRIPTION OF THE SPOROPHORE OF POLYPORUS DRYOPHILUS 



Pileus thick, unequal, smooth to irregular nodulose, often convex below, unguliform 

 (PI. IX, fig. s), subglobose (PI. IX, fig. i) or even applanate (PI. X, fig. i), simple or 

 rarely subimbricate (PI. X, figs. 2 and 5), rigid, 4 to 22 cm. broad by 3 to 13 cm. wide 

 (measured from front to rear of sporophore) by 2.5 to 21 cm. thick (measured from pore 

 surface to top of sporophore); surface at first densely tomentose, becoming scabrous to 

 smooth with age ; tomentum rather stiff, deciduous, short, maize yellow to ferruginous; 

 surface of weathered sporophoresafter the tomentum has partially disappeared, zonate, 

 zones several, narrow, extending entirely around the pileus near its margin (PI. IX, 

 fig. 3); margin in immature specimens thick, usually obtuse (Pis. IX, figs, i and 5, and 

 X, figs. I and 2), concolorous or slightly pallid, entire or undulate; context dual, con- 

 sisting of a hard granular core, surrounded except in the rear by a thin fibrous layer; 

 core subglobose to pulvinate, 3 to 10 cm. thick, ferruginous to cinnamon brown, gran- 

 ular, often with white mycelial strands ramifying through it (PI. IX, fig. 2); fibrous 

 layer on upper surface of core a mere pellicle about 0.5 mm. thick, expanding in mature 

 specimens into a border (PI. IX, fig. 4) i to 3 cm. wide and 5 to 15 mm. thick; fibrous 

 layer between tubes and core thin, i to 15 mm., usually not over 6 to 8 mm., fibrous 

 layer zonate, concolorous; tubes slender, concolorous or slightly paler than core in 

 some specimens, rather fragile in age, 5 mm. to 3.5 cm. long, shorter near margin of 

 sporophore, usually about i cm. long; mouths regular when young, but becoming 

 somewhat irregular and angular at maturity (Pis. IX, fig. 6, and X, fig. 8), two or three to 

 a mm., glistening, grayish when young, becoming hazel to russet with age, edges thin; 

 spores broadly oval, smooth, ferruginous, 4.8 to 8 by 3.4 to 6.4/1, average size 6.54 by 

 4.85/1 when on oak (PI. IX, fig. 6), 4.8 to 6.4 by 3.4 to 5.6/1, average size 5.82 by 4.05/1 

 when on poplar (PI. X, fig. 8); cystidia none; hyphae ferruginous, 4 to 6,u. The 

 sporophores found on oak in Arkansas and in the eastern portion of the United States 

 often have shorter tubes (PI. IX, fig. 4), slightly smaller spores, and a more applanate 

 pileus than those found in the Western States (PI. IX, fig. 2). 



DISTRIBUTION OF POLYPORUS DRYOPHILUS 



The rot caused by Polyporus dryophilns is very widely distributed in 

 the United States, having been found in 23 States: Arizona, Arkansas, 

 CaHfornia, Colorado, Ilhnois, Kansas, Louisiana, Maine, Maryland, Mis- 

 sissippi, Missouri, Nebraska, New Hampshire, New Mexico, New York, 

 North Carohna, Ohio, Oklahoma, Oregon, Pennsylvania, Tennessee, 

 Texas, and Wisconsin. Authentic specimens of the fungus have also 

 been examined from the following foreign countries: Austria, Denmark, 

 Finland, France, Germany, and Sweden. The sporophores of the fungus 

 are frequent and the rot caused by the fungus is exceedingly common in 

 New Mexico, Arizona, and California. 



DISTRIBUTION IN EUROPE 



Polyporus dryophilus is known to occur in Europe as follows, the jimior writer 

 having examined authentic specimens: 

 Germany (?); 



On Quercus sp. (F. P. 12404)'. 



* " F. P." = Forest-PathoJogy Investigations number. 



