A NEW GYMNOSPORANGIAL CONNECTION 
F. D. Fromme 
The genus Gymnosporangium, according to Kern, 1 is repre- 
sented in North America by some 32 species. Of these, all but 
one are heteroecious, the aecial stages being found on members 
of the Hydrangeaceae, Rosaceae, and Malaceae families, while the 
telial stages are restricted to the family Juniperaceae. The single 
autoecious species, Gymnosporangium bermudianum, bears all its 
spore forms on species of Juniperus. Because of this limited 
selection of hosts, as well as their unique morphological charac- 
ters, the members of this genus have been classed among the most 
restricted and isolated of the rusts. Until recently, no aecial 
stages were known on other than pomaceous hosts and it had been 
assumed that they were restricted to the family Malaceae. The 
first exeception to this rule was established by Arthur 2 in 1908 
when Gymnosporangium exterum on Juniperus virginiana was 
successfully cultured on Porteranthus stipulatus, thus adding the 
family Rosaceae to the list of aecial hosts. The further addition 
of the family Hydrangeaceae was made by Arthur 3 in 1911 when 
Gymnosporangium gracilens was shown to have its aecial stage on 
Philadelphus and related genera. These three families are evi- 
dently closely related and are all included under the order Rosales. 
As a result of a series of observations, followed by successful 
inoculation tests, the writer is now able to extend the list to in- 
clude a fourth family, the Myricaceae, and to establish the identity 
of Aecidium myricatum Schw. and Gymnosporangium Ellisii 
(Berk.) Farl. This work is a part of the series of “ Cultures of 
Uredineae ” that have been in progress at the Purdue Experiment 
Station under the direction of Dr. J. C. Arthur since 1899, and is 
published by permission in advance of the 1914 report. 
The establishment of the connection between Aec. myricatum 
1 N. Am. Flora 7: 188-211. 1912. 
2 Mycologia i: 253-254. 1908. 
s Mycologia 4 : 63. 1911. 
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