276 FOUNDATIONS OF BOTANY 



The "rust" of wheat and the "smut" of corn repre- 

 sent groups numbering only a few hundreds of species, 

 which are very important because they are all parasites 

 on living plants, many on our most important economic 

 plants. 



Fig. 191, representing another small group of destruc- 

 tive parasites, shows clearly how a parasitic fungus grows 

 from a spore which has found lodgment in the tissues of 

 a leaf and pushes out stalks through the stomata to dis- 

 tribute its spores. 



