194 



BOTANY. 



aecidiospores, and of tlie second uredospores, while tie tliird name 

 is retained as the scientific name of the genus. 



The sporids cannot ordinarily produce rust directly upon wheat, 

 probably because of the toughness of the epidermis ; but it has been 



Fio. 114.— Wheat-rust. A and B, Black-rust spores germinating and 

 producing sporids, sp ; C, fragment of a Barberry-leaf with a spond, sp. 

 germinating and penetrating the epidermis; I), showing manner 

 germination of Red-rust spore. All highly magnified. 



of 



shown that when sporids germinate upon very young leaves of wheat- 

 seedlings they penetrate the epidermis and then soon give rise to a 

 red-rust stage. In such cases the cluster-cup stage is omitted. Pos- 

 sibly the rusts upon the spring wheat, oats, and barley in the Mis- 



