594 Murrill: Polyporaceae of North America 



very deeply colored, while others are so pale as to appear almost 

 hyaline, especially when not fully matured. 



The largest species is /, hirsutus, sometimes over 30 cm. in 

 diameter, while the smallest, /. pusillus, is rarely over two or three 

 millimeters across. As regards the distribution of our species, two, 

 /. hirsutus and /. radiatus, occur in Europe and in temperate North 

 America ; three others, /. perplexus, I. dryophilus and /. amplec- 

 tc/is, appear to be confined to temperate regions of North America; 

 while the remaining six are known only from certain localities in 

 tropical America. 



Synopsis of the North American species 



1. Spores deep brown in color. 2. 

 Spores faintly tinted with brown. 5- 



2. Surface of pileus hirsute, tubes luteous, margin obtuse ; plants of large size and two 



centimeters or more in thickness. I. /• hirsutus. 



Surface of pileus conspicuously tomentose, margin acute ; plants of medium size and 



one centimeter or less in thickness. 2. /. perplexus. 



Surface of pileus glabrous or finely tomentose. 3- 



3. Pileus 8 cm. or more in width, rigid, ferruginous throughout, margin rather obtuse. 



3. /. dryophilus. 

 Pileus 5 cm. or less in width. 4- 



4. Surface of pileus very rimose, tubes 2 cm. long. 4. 1. texanus. 

 Surface of pileus rugulose and zonate, but not rimose, tubes I cm. long. 



5. I. jamaitcnsis. 



5. Pores scarcely visible to the unaided eye. 6. 

 Pores conspicuous. 7- 



6. Pileus thick, azonate, margin obtuse, hymenium dull. 6. /. corrosus. 

 Pileus thin, zonate, margin very sharp, hymenium glistening. 7. /. Wihonii, 



7. Plants minute, only a few millimeters across, erumpent from lenticels of dead twigs. 



8. /. pusillus. 

 Plants of medium size. 8. 



8. Surface soft, anoderm, sporophores growing on living shrubs, often encircling the 



smaller branches. 9- 



Surface hard, becoming encrusted, sporophores found on decaying wood. 



9. /. radiatus. 



9. Hymenium very concave, umbrinous, margin sharp and depressed. 10 I. ampleclens. 

 Hymenium plane or nearly so, becoming almost black, margin rather blunt and not 



depressed. »■ I. fruticum. 



i. Inonotus hirsutus (Scop.) 

 Boletus hirsutus Scop. Fl. Cam. ed. 2. 2: 46S. 1772. 

 Boletus spongiosis Lightf. Fl. Scot. 1033. 1 777- 

 Boletus hispidus Bull. Herb. Fr. pi. 210. 1784. pi. 493. 1791. 



