PUFFBALLS AND RELATED FORMS (GASTEROMYCETES) 389 



In Figure 344 is a Bracket Fungus which causes a disease 

 known as White Heart Rot. This disease occurs on fruit trees 

 and many forest trees. The spore enters through a wound and 

 starts the mycelium which penetrates and transforms the heart 

 wood into a white pulpy mass. In Figure 345 is shown another 

 Bracket Fungus which attacks trees in a similar way and causes 

 the wood to rot and become reddish brown or black. It produces 

 the Red Heart Rot. There are many other destructive forms 

 which concern the forester and horticulturist. They start in 



FIG. 344. One of the Bracket Fungi, Fomes igniarius, living on the trunk 

 of a living Aspen. It attacks various trees, destroying the wood and causing 

 much damage. From Bulletin 189, Bureau of Plant Industry, U. S. Dept. 

 of Agriculture. 



wounds where there is some decaying matter, and in pruning it 

 is necessary to guard against the entrance of these Fungi. 



Puffballs and Related Forms (Gasteromycetes). On account 

 of the complexity of their sporophores, the Gasteromycetes are 

 considered the highest of all Fungi. They are saprophytes, 

 growing on decaying wood, leaf mold, rich humus, and manure. 

 They require about the same conditions for growth as do the Toad- 

 stools and Mushrooms and are often found growing with them. 

 There are about 700 species, many of which are edible. The 

 sporophore of these Fungi is usually more or less globular in form 

 and the hymenium is enclosed. 



