FUNGI: THE RUST FUNGI 287 



was always more badly rusted on the leeward side of barberry 

 bushes. As early as 1760 laws were passed in Massachusetts 

 requiring barberry bushes to be destroyed. A little later a 

 Swedish schoolmaster, Schoeler (in 1816), carried barberry leaves 

 with the cluster cups into a rye field and rubbed the leaves on to 

 the rye, so that he could see the masses of yellow cluster-cup spores 

 on the rye leaves. These rye plants became badly infected, while 

 the remaining plants around them remained healthy. Finally, 

 in 1864-5, de Bary, a celebrated German botanist, demonstrated 



Fig. 263. 



Cedar apples, the winter condition. Abnormal growth of the cedar caused by a fungus 

 (Gymnosporangium macropus). The masses of spores ready to ooze out are in the little pits 

 with the conical elevations. 



by experimental studies the connection of the cluster cup on bar- 

 berry with the uredo and teleutospores on wheat, his investiga- 

 tions undoubtedly being stimulated by those of a renowned French 

 botanist, Tulasne, who had previously shown the connection of the 

 uredo and teleuto stages. These studies have since been verified, 

 both in Europe and in the United States, in regions where the 

 barberry grows. 



454. Other grain rusts. There are a number of other rusts 

 which attack wheat and other cereals. One of the most destruc- 

 tive of these in this country is Puccinia rubigo-vera. In some 

 regions in the United States this rust is more abundant and does 

 more injury to the wheat than the Puccinia graminis. 



