FUNGI: RUSTS. 



'33 



294. Uredospores can produce successive crops of uredospores. Tiie uredo- 

 spores are carried by the wind to other wheat or grass plants, germinate, 



Fig. i57. 



Section through leaf of barberry at point affected with the cluster-cup stage of the wheat 

 rust; spermagonia above, aicidia below. (After Marshall-Ward.) 



form mycelium in the tissues, and later the pustules with a second crop of 

 uredospores. Several successive crops of uredospores may be developed in 





B 



Fig. 158. 



A , section through sorus of black rust of wheat, showing teleutospores. /?, mycelium 

 bearing both teleutospores and uredospores. (After de Bary.) 



one season, so this is the form in which the fungus is greatly multiplied and 

 widely distributed. 



