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60 Journal of Mycology [Vol. 11 



In addition to the foregoing results five species of rusts 

 were grown, establishing aecidial and teleutosporic connections, 

 not heretofore recorded. The species are heterpecious with one 

 exception. 



i. Melampsora Bigelowii Thiim. Three collections of 

 teleutospores on Salix were secured, but only one, which was 

 obtained at Racine, Wis., on Salix amygdaloidcs Anders., and 

 forwarded by Dr. J. J. Davis, could be made to germinate. This 

 was sown, May io, on Larix decidua Mill., and twenty days 

 later both spermogonia and aecidia were observed in abundance, 

 although they had probably first made their appearance some 

 days earlier. On the same date it was sown on Euonymus 

 obovatus without result. A further sowing on Larix decidua 

 was made on May 25, and on June 4 spermogonia began to 

 appear in great abundance, followed on June 10 by an equal 

 abundance of aecidia. The aecidia are of the typical caeoma- 

 form, and are very similar to those of Melampsora Medusae, 

 the chief difference being in the spores, which are somewhat 

 more distinctly and coarsely verrucose than in the poplar form. 



The only American collections of aecidia on Larix, that 

 have come to my attention, were made by E. W. D. Hoi way 

 at Mt. Temple, Aug. 22, 1902, and Laggan, Aug. 23, 1902, 

 both places in Alberta, Canada, and both collections on Larix 

 Lyallii Pari. These collections agree perfectly with the aecidia 

 raised in cultures. A comparison of the numerous collections of 

 willow rust in my own herbarium, numbering 80 packets, and 

 representing all sections of the United States and Canada from 

 the Atlantic to the Pacific, shows that both the uredosporic 

 and teleutosporic stages agree closely with one another, and 

 with those on the material used in the culture. 



A comparison with European collections shows the Ameri- 

 can form to be very different from any European species. The 

 nearest approach to the American form is Melampsora Larici- 

 epitea Kleb., the most common willow rust of Europe. The 

 two differ, however, in a very marked way. The American 

 form has all three sorts of spores considerably larger, the spores 

 of the aecidia and uredo have walls twice as thick, the pores 

 are far more evident, and the papillae on the surface are much 

 closer together. 



The name which I have adopted for this common willow 

 rust was given by Baron von Thuemen to a collection made 

 in California on Salix Bigelowii, which he stated had been 

 received from the herbarium of Dr. W. G. Farlow. Von Thue- 

 men's herbarium was burned some years ago, and the type is 

 consequently destroyed. In reply to an inquiry regarding the 

 matter, Dr. Farlow states that he does not recall sending such 

 a specimen to von Thuemen, and is unable to find a correspond- 



