54 



The chief characters used in this temporary grouping are the 

 position of the stem, the habitat of the plant, the coherency, size, 

 and arrangement of the tubes, the presence of a veil, viscid dots 

 on tubes and stem, red mouths to the tubes, a lacerated and 

 deeply-grooved stem, adnate or free tubes, a yellow powder 

 covering the entire plant, and flesh-colored or blackish-brown 

 spores. 



The spores vary but little, considering the number of species, 

 most of them being fusiform in shape and ochraceous-brown to 

 ferruginous in color. Flesh-colored, pale-yellew, purplish-brown 

 and blackish-brown spores occur, but they are exceptional. A 

 greenish tint is noticed in the fresh spores of many species, but it 

 usually disappears on drying. 



Certain other characters, such as reticulations on the stem, 

 viscidity, changes in color of flesh or tubes, and inconspicuous 

 surface coverings, often vary with age, locality or the weather in 

 some species, and may or may not be reliable, but may be con- 

 veniently used at times in connection with more important charac- 

 ters to distinguish certain groups. 



A key to these provisional groups is given below, each group 

 being designated by a letter. Well-known species have been 

 used in the key as examples of various groups, as a means of 

 ready identification and comparison. 



Groups of North American Boleti 



Tubes separated from each other ; stem lateral ; plants found on decaying stumps, 

 trunks or roots. (^Fisiulina hepatica. ) A 



Tubes attached to each other ; stem central, rarely eccentric ; plants terrestrial, except 

 in very rare instances. 

 Tubes arranged in radiating rows. (^Boletinus porosus.) B 



Tubes usually small, not arranged in radiating rows. 

 Pileus conspicuously floccose. 



Spores blackish-brown. [Strobilomyces strobilaceus. ) C 



Spores ferruginous. {^Boletus Ananas.) D 



Pileus glabrous or subtomentose. 



Stem annulate. ( Bole/us htieus. ) E 



Stem exannulate. 



Stem and tubes glandular-dotted with a gummy secretion that 



hardens and turns black soon after exudation. {Bo/eius 



gratinla(us. ) F 



Stem shaggy and lacerate, with deep reticulated furrows ; spores 



olive-brown. [Boletus Kussellii.) G 



