FUNGI: RUSTS. 



407. Uredospores can produce successive crops of uredospores. Tue uredo- 

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



Fig. 218. 



g. 21. 



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

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



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

 uredospores. Several successive crops of uredospores may be developed in 



B 



Fig. 219. 



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

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



B, mycelium 



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

 widely distributed. 



