LIFE HISTORIES OF FUNGI 275 



wind to the leaves of nearby barberry bushes, where they 

 germinate. The resulting myceHum penetrates the epi- 

 dermis, and ramifies between the cells of the leaf paren- 

 chyma, from which it absorbs nourishment. Under 

 certain circumstances, as for" example in Australia where 

 barberries do not grow, the barberry stage is eliminated. 

 Soon this myceHum develops a reproductive structure 

 called the pycnium (pycnidium or spermagonium), which 

 breaks through the upper epidermis and produces innu- 

 merable pycniospores (spermatia). The real nature of 

 this structure is not known. 



OUTLINE OF LIFE HISTORY OF WHEAT RUST 

 Rust on Grain 



Uirediniospores (early summer) Teliospores (late summer) 



Germination Rest {nuclear fusion) 



4^ >K . 4^ 4^ 



Mycelium Germination 



4^ 4^ 4^ 4^ 



Urediniospores Basidium (reduction) 



4^4^ 4^ 



Germination Sterigmata 



^ ^ 4^ ^ 



Etc. Basidiospores (sporidia) 



' To barberry 



^. . ^ . 



Pycnia ^cia (cell-fusion) 



4' 4^4^ 



? ^ciospores 



Rust on grain 



Near the lower epidermis are formed the "cluster- 

 cups," or mcia^ (aecidia). They break through to the 

 ' Sing, tecium. 



