30 



then is one that gets all its nourishment by robbing some other 

 living plant or animal. 



Saprophtic fungi seldom does much damage. Under proper 

 conditions, however, some of them become parasitic or semi- 

 parasitic in their habits and then are more or less injurious. It 

 is to the parasitic fungi that we must look for our injurious 

 forms. These send their vegetative threads through the tissues 

 of other plants causing disease and often death. The plant 

 upon which a fungus grows is called the "host plant" or the 

 "host." 



METHODS OF REPRODUCTION IN THE PRINCIPAL KINDS OF PARASI- 

 TIC FUNGI. 



The greater part of our injurious fun^i belongs to the kinds 

 commonly known as, THE BLIGHTS, THE MILDEWS, THE WHITE 



RUSTS, THE SMUTS, THE RED OR BLACK RUSTS, and THE LEAF SPOT 



FUNGI. In order that all may have some idea of the ways these 

 plants perpetuate themselves, a short account of the various 

 methods of reproduction is appended. 



THE DOWNY MILDEWS AND WHITE RUSTS. 



In both of these there are two kinds of spores or reproductive 

 bodies, one kind born on mycelia within the tissues of the 

 host plant, remains there until the tissues decay and fall away, 

 which is usually the following spring. These spores are known 

 as resting spores. They serve to carry the fungus over to the 

 next season. That is performing the same function as do the 

 seeds of the flowering plants. The other kind of spores {conidia ) 

 are born upon upright branches of the vegetative threads. 

 In the downy mildews these spores are born outside, on the sur- 

 face of the host plant, upon many- forked branches, and give the 

 surface a light colored down-like appearance. In the white rusts 

 the spores are developed beneath the surface of the host, form- 

 ing shining white spots and later bursting through the epidermis, 

 giving the surface a white powdery appearance. In nearly all 

 cases this last kind of spore is produced in much greater quanti- 

 ties than the resting spores, and as they germinate readily serve 

 to produce a more rapid multiplication of plants and a wider 



