THE BOLETACEAE OF NORTH AMERICA— I 



William A. Murrill 



The Boletaceae are fleshy tube-bearing fungi, terrestrial for 

 the most part, and, with one or two exceptions, centrally stipitate. 

 They differ from the Polyporaceae chiefly in their fleshy con- 

 sistency and terrestrial habit. Most of them are edible, but a few 

 species are said to be distinctly poisonous. 



The family shows few lines of cleavage, although a number 

 of genera have been proposed since Linnaeus included all tube- 

 bearing fungi in the single genus Boletus. S. F. Gray, in 182 1, 

 divided the group into three genera, Suillus, Pinuzza and Lecci- 

 num. Strobilomyces was separated by Berkeley in i860, and 

 Boletinus by Kalchbrenner in 1877. More recently, Karsten, 

 Quelet, and Patouillard have each originated or adopted a sys- 

 tem of classification for the group involving a number of genera, 

 which will be discussed in their proper order in the following 

 pages. 



Synopsis of the North American Genera 



Tubes arranged in radiating rows. 



Stipe annulate. 

 Stipe exannulate. 



2. 



1. 



Boletinus. 

 Boletinellus. 



Tubes not arranged in radiating rows. 



Stipe either glandular-dotted or annulate. 



Stipe annulate, glandular-dotted in some species. 



Spores brownish-black, rough, subglobose. 

 Spores ochraceous to yellowish-brown, smooth, 

 usually oblong-ellipsoid. 

 Sporophore covered with a conspicuous 



yellow powder. 

 Sporophore not covered with a yellow 

 powder. 



Pileus floccose-verrucose, dry. 

 Pileus smooth, viscid. 



3- 



Strobilomyces. 



Pulveroboletus. 



Stipe glandular-dotted, exannulate. 

 Stipe neither glandular-dotted nor annulate. 



5. 

 6. 



Boletellus. 



Boletus. 



Rostkovites. 



Spores hyaline, often becoming yellowish ; stem 



hollow, not reticulated. 



4 



8, 



Gyroporus. 



