24 



Mycologia 



The aecidia on the leaves and young stems appear to be scat- 

 tered rather sparingly over the long hypertrophied or thickened 

 portions. A marked transformation of the leaf seems to accom- 

 pany infection. Every leaf that we found bearing aecidia had 

 made a coil of one or two turns like a ram's horn, which, in a way, 

 quite effectually conceals the rust from view. Roestelia trans- 

 formans was originally described as causing considerable defor- 

 mation of the Aronia leaves, yet a great many leaves infected are 

 in no way misshapen. Further collections of this rust on Comp- 

 tonia may prove that it does not always cause the leaf to roll up. 

 The peridia are whitish, with very brittle segments which soon 

 disappear, or break off and become scattered over the under sur- 

 face of the leaf. The spores are globoid, varying in size from 25- 

 35 fx. They appear to be rather dark-orange or salmon-colored in 

 mass. The spore wall is finely warted or echinulate. This rust 

 resembles Aecidium myricatum, known so far to occur only on the 

 bayberries. Cronartium Comptoniae has been found also on 

 species of Myrica, and it is not surprising to find that a Gymno- 

 sporangium capable of infecting Myrica could also infect Comp- 

 tonia as the two genera are closely related. 



Fromme (1914) has shown that Aecidium myricatum is con- 

 nected with Gymnosporangium Ellisii on Chamaecyparis. In 

 1914 Dodge (1915) tried to infect Comptonia with G. Ellisii with- 

 out success. The trial host plants lived only about two weeks 

 after the inoculations were made, but as the rust appeared on 

 the Myrica within a week it was presumed that this Gymno- 

 sporangium would not infect the sweet fern. The teleutospore 

 material used at the time was in the best of condition, so that 

 failure was not on this account. We made some attempts to 

 infect the sweet fern with the spores of G. Ellisii under controlled 

 conditions in the greenhouse, but the season was so far advanced 

 that the sweet fern could not be made to survive transplanting, 

 and the spores of G. Ellisii were past their prime. 



Aecidium myricatum on the bayberry is especially abundant at 

 Toms River; in places the rust appears to be destructive, espe- 

 cially where it attacks the branches or main stems. The southern 

 white cedar and sweet fern grow together in many localities along 

 the coast, but we have found the sweet fern rust only at this one 



