46 



Mycologia 



section. Whatever the conditions, they have been very favorable 

 for the prolific reproduction of the hawthorns and illustrate an 

 interesting development of recognized species. 



With the close association between the two hosts favorable 

 conditions are present for the development of Gymno sporangium 

 rusts. The following species are found established-: Gymno spor- 

 angium germinate (Schw.) Kern, Gymno sporangium globosum 

 Farlow, and Gymno sporangium J uniperi-virginianae Schw. 

 These three species are found severely infecting the above men- 

 tioned hosts. 



Fig. 2. Upper portion of a hawthorn showing the numerous hypertrofied 

 branches as the result of infection of G. germinale. 



The telial infection of G. germinale which occurs upon the 

 trunks and branches of the cedars is most prevalent on the young 

 growth, which is often completely girdled. On the hawthorns 

 the most serious infection is with this rust. The young growth, 

 modified branches, and terminal buds present abnormal hyper- 

 trofied developments when infected, as shown in figure 3. 

 Severely infected trees with this species of rust present," from a 

 distance, an appearance similar to a black-knot infection on 



