208 



BULLETIN 193. 



as some shrinkage had taken place, it presented the very fine 

 divisions into minute blocks described above. I then searched 

 more carefully for some fruit form of the fungus and found at 

 the ground level, buried under leaves, a fruit body of the Polyp- 

 orus borealis between two buttresses of the base of the trunk. 

 The tree was not felled, and -consequently there was no oppor- 

 tunity of ascertaining the special mode of infection in this case. 



POLYPORUS SULPHUREUS. 



The sulphur polyporus has a very wide distribution and occurs 



on a great variety of broad 

 leaved trees as well as on certain 

 of the conifers. It is known on 

 the apple, walnut, butternut, 

 locust, oak, ash, pine, hemlock 

 spruce, and other trees. It 

 occurs on living trees, the fruit 

 bodies growing from knot holes 

 or wounds from the mycelium in 

 the heart of the tree ; or the 

 fruit bodies arise from portions 

 of the trunk killed by the fun- 

 gus. It is also a very common 

 fungus on dead and decaying 

 logs, stumps and roots. 



The plant is easily recognized 

 by the yellowish color of the caps 

 which are of the shelving form, 

 sometimes scattered, but more 

 often closely overlapping. 

 Sometimes the caps are so 

 closely crowded as to form a large tubercle 20 to 25 cm. or more 

 in diameter. The upper surface of the cap is a bright orange red, 

 while the lower surface, the honey-combed fruit surface, is sul- 

 phur yellow. The fruit bodies are rather soft, the color soon 

 fades, they are quickly attacked by insects, or decay after sev- 

 eral weeks. They are short lived therefore, while the mycelium 

 within the trunk is perennial, or at least lives from year to year 

 without an annual infection. 



64. Polyporus sulphureus. 

 Large tubercular fruit body 

 on oak. 



