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. 
