96 



ELEMENTARY BOTANY. 



smaller flask-shaped bodies, called spermogonia (Fig. 121), 

 containing hair-like filaments, which break up into exceed- 

 ingly small bodies, called the spermatia. The exact function 



Spermogonia „ 



Spermogoma 



^Ecidium 



Jlcidmm 



Fig. 121. 



of these is not known. The Escidiospores germinate, and 

 when on the proper host-plants the germ-tube grows through 

 the stomates. A dense mycelium is then formed in the paren- 

 chyma of the leaf ; from this mycelium grow pedicelled spores, 

 called uredospores. They form, when they burst through the 

 epidermis, orange-colored spots, called Red Rust. This stage 

 was formerly designated as the genus Uredo (Fig. 122). The 



Fig. 122. 



uredospores germinate quickly, and from their mycelium 

 other uredospores are produced, and this process may con- 

 tinue a great length of time. Finally, from the same myce- 

 lium are produced thick-walled brown or black spores, called 

 teleutospores (Gr. teleuta, end). These may be one-celled (as in 



