EXERCISE 88 

 WOOD-ROTTING FUNGI 



Materials. Examine standing trees and fallen logs for any large 

 fungi found growing upon living or dead wood. Bracket or shelf 

 fungi and the oyster-shell fungus are common. Collect these, 

 together with pieces of the wood and bark to which they are 

 attached. 



Directions for work. In the laboratory examine the collected 

 materials. Note that the fruiting bodies often have no stalk, 

 or a very short one, and that this stalk is in many forms 

 attached at the edge of the cap rather than in the center. The 

 most marked feature of the group to which most of the wood- 

 rotting fungi belong (Polyporacece) is that the spores are borne 

 not on gills, as in the mushrooms {Agaricacece), but in numerous 

 small pores found on the under side. Any gill fungi found in 

 the collection probably belong to the mushrooms. 



Examine the wood and bark for the fine, whitish fibers of 

 the mycelium and trace it through the wood as far as possible. 

 Compare the fungus-infected wood with sound wood as to weight, 

 hardness, strength, and color. 



Do you find results of fungus attack in living trunks or 

 branches or only in dead ones ? Is it possible that these fungi 

 cause the death of wood ? If so, what would be their impor- 

 tance with relation to the lumbering industry? 



In the case of any which attack only dead wood, what is 

 their importance in the forest? What is their possible impor- 

 tance with relation to telephone poles, fence posts, and railway 

 ties, and in lumber yards ? What direct evidence have you of 

 their actual importance in the latter cases ? 



Reference 



HUMPHREY, C. J. ** Timber-Storage Conditions," Bulletin No. 510, 

 U. S. Dept. Agr. 



[Ill] 



