30 FOREST TREE DISEASES. 



which the spores are developed. Examples are the 

 fungus causing the stringy brown rot of white fir 

 (Echinodontium tinctorum, PI. XVII), which is per- 

 haps the greatest enemy of this species ; and the fungus 

 Ilydnum erinaceus, which causes a destructive rot of 

 the heartwood of oak. While the spiny fungi are not 

 found on many species of trees, they are very injurious. 



GILL-BEARING FUNGI. 



This group takes its name from the regular blade- 

 like gills on the underside of the fruiting bodies, radiat- 

 ing from the stalk (mushrooms). The spores are de- 

 veloped on the sides of the gills. 



FUNGI WITH FRUITING BODIES NOT IN THE FORM OF STOOLS 

 OR CRUSTS. 



LEAF AND TWIG FUNGI. 



The fruiting bodies of leaf and twig fungi present a 

 great variety of forms, often, however, they appear as 

 black spots or lines. They, too, produce spores, which 

 carry the disease to sound organs. 



ATTACK ON VITAL AND NONVITAL PARTS OF THE TREE. 



The fungi which attack forest trees may be di- 

 vided roughly into two groups those which cause 

 disease or death of vital parts of a tree and those which 

 destroy nonvital parts. 



FUNGI WHICH ATTACK VITAL PARTS OF THE TBEE. 



An example of the first group are the needle fungi. 

 Partial destruction of the foliage is not always fatal 



