110 



Mycologia 



technical descriptions of the sporophores, however, have been 

 given by Murrill in North American Flora 9 : 104, 107. 1908. 



The junior author is responsible for the descriptions given, and 

 for the micro-chemical studies of the rots reported in this article. 

 The field notes on Fomes earlei and F. texanus were made by 

 both authors. 



White Heart Rot of Juniper 



FoMES JUNIPERINUS (Schrenk) Sacc. & Syd. Sacc. 

 Syll. 16: 151. 1902 



Folyporus juniperinus Schrenk, Bull. U. S. Dept. Agr. Veg. Phys. 



and Path. 21: 9. 1900. 

 Pyropolyporus juniperinus (Schrenk) Murrill, Bull. Torrey Club 



30: 116. 1903. 



Rot white, or brownish-white in partially rotted areas, forming 

 holes in the heart wood. These holes have white borders consist- 

 ing of delignified wood tissues, which rather abruptly change both 

 in structure and color until the normal condition of the sound 

 wood is reached. Long, white fibers of pure cellulose extend 

 into the cavity, which usually contains a yellowish mass, consist- 

 ing of wood fibers intermixed with the mycelium of the fungus. 

 The holes vary from one to three inches in diameter and extend 

 longitudinally in the tree for several inches (4-6) ; or successive 

 holes may coalesce into one long hole ; or there may be several 

 holes in one cross section. The white delignified tissue that 

 borders the holes is firm and appears to be sound, but a micro- 

 scopic examination shows that the middle lamellae and medullary 

 rays have disappeared, leaving the individual tracheids with walls 

 of pure cellulose. The bordered pits are also corroded until they 

 appear as regular perforations in the tracheids. 



Later the delignified wood is gradually destroyed, thus produc- 

 ing the holes in the trees. There seems to be a radial limit to the 

 activity of this fungus as the holes increase in size up to a cer- 

 tain diameter, beyond which all enzymotic action stops and the 

 hole ceases to grow in diameter, but may continue to grow longi- 

 tudinally. Around the edges of such holes the delignification and 

 the absorption of the resulting cellulose seem to progress at about 

 the same rate, as the attacked wood gives only a faint reaction 

 for pure cellulose. This description is made from a portion of 

 the type material of the rot. 



Pileus woody, ungulate, length 3-7 cm., breadth 5-9 cm., thick- 



