Fig. 63. Puccinia graminis. i, leaves of wheat plant with rust 

 pustules of the uredo stage ; 2, a rust or uredo sorus, or group of spores, 

 x 10 ; 3, uredospores in various stages of development, X3Oo; 4, uredo- 

 spore germinating, x 300 ; 5, portion of culm of a wheat plant showing the 

 dark streaks formed by the sori of the teleutospore stage on the sheath of 

 a leaf ; 6, teleutospores in various stages of development, x 300 ; 7, a 

 teleutospore that has germinated and produced a germ-tube bearing three 

 secondary spores, X4OO; 8, a barberry leaf bearing several clusters of 

 aecidia ; 9, section of an aecidium showing the pseudoperidium or external 

 protective covering, a, enclosing numerous chains of aecidiospores, xsoo; 

 10, two aecidia seen from above, slightly mag. ; u, sporules on sterigmata 

 from a spermogonium, x 300. 



