FUNGI 



IS.") 



called wcidiospores. They are formed in long chains in little fringed 

 cups, or cecidia, which appear in groups on the lower side of the leaf 

 (Pig. 328). These orange or yellow secidia are termed cluster-cups. 



In Pig. 329 is shown a cross-section of one of the cups, outlining 



the long chains of spores, and the 

 /^~ v- _, <k>*v mycelium in the tissues. 



r. ,, 



LV 





Tlie aecidiospores are formed in 

 the spring, and after they have been 

 set free some of them lodge on wheal 

 or other grasses, where they germi- 



328. Leaf of barbeny with eluster-cup;. nate immediately. The germ-tube 



enters the leaf through a stomate, 

 whence it spreads among the cells of the -wheat plant. During sum- 

 mer one-celled urcrto&pores ("blight spores") are produced in a man- 

 ner similar to the teleutospores. These are capable of germinating 

 immediately and serve to disseminate the fungus during the summer 

 on other wheat plants or grasses (Pig. 330). Late in the season, 

 teleutospores are again produced, 

 completing the life cycle of the 

 plant. 



.Many rusts beside Puccinia 

 graminis produce different spore- 

 forms en different plants. The 

 phenomenon is called h U racism, 

 and was first shown to exist in 

 the wheat rust. Curiously enough, 

 the peasants of Europe had ob- 

 served and asserted that barberry 

 bushes ran-.' wheat to blight long 

 before science explained t be rela- 

 tion between the cluster-cups Oil 



ft - > , ,- . barberry and the rust 



-,/' >i*' on wheat. The true 



( j \^J relation was actually 

 demonstrated, as lias 



Uredo i i since been done for manyother rusts on their respective 



wheat roat. bosts by sowing the ceeidiospores on bealthy wheat 

 plants and thus producing the rust. The cedar apple is another rust, 

 producing the curious swellings often found on the branches ol red 

 cedar trees. In the Bpring the teleuto out from the 



"apple" in brownish yellow masses. It has been found that these 

 attack various fruit trees producing Gccidio on their leavi 



j 



V 







Section through a cluster-cup on 

 barlx 



