CONTEXT AND PORES WHITE OR PALE. 



light, spongy. Pores very large, irregular, 1-3 cm. long, 2-3 mm. wide, 

 light tissue, concolorous with the flesh. Spores 8-10 mic., hyaline, 

 smooth, with large guttae. 



Fig, 666. 



Polyporus obtusus. 



This is a remarkable species not rare in portions of the United 

 States. It generally grows on living black oaks, causing a heart rot 

 that eventually kills the tree. It is said not to infect the white oaks 

 or red oaks. This fungus is noteworthy for its soft, spongy flesh, light 

 weight, and large pores. We have never seen it growing, but we 

 think fresh specimens are more yellow than the dried ones. 



Polyporus obtusus was most probably the plant that Schweinitz 

 called Sistotrema spongiosum, changed by Fries to Polyporus laby- 

 rinthicus, of which no specimen exists. It is found in Schweinitz's 

 herbarium as Polyporus unicolor, but does not agree with his descrip- 

 tion of unicolor. The first specimen to reach Europe was collected 

 by Drummond (near New Orleans, probably), and named in ms. 

 by Klotzsch as "Polyporus Drummondii Klotzsch," but is not the 

 plant published under that name. Berkeley published it as Polyporus 

 obtusus. The plant is not infrequent in the United States in sections 

 where the black oak grows. In Europe it is not surely known, though 

 we should here refer a specimen collected in Hungary by Kmet, which 

 was referred to Polyporus Schulzeri, and probably is Polyporus 

 Schulzeri according to the poor picture that Kalchbrenner gave of it. 

 It has never been collected in western Europe. In the New York 



324 



