VOLUME LXV NUMBER 4 
ELHE 
BOTANICAL. -GsAweere 
APRIL 1918 
CARDUACEOUS SPECIES OF PUCCINIA’ 
I. SPECIES OCCURRING ON THE TRIBE VERNONIAE 
H. S. JACKSON 
This is the first of a proposed series of papers dealing with the 
species of Puccinia occurring on the Carduaceae. It is planned to 
discuss in separate articles the species recorded on the host genera 
included in the different tribes of the family. The series is the 
result of a study made in connection with the preparation, by the 
writer, of the manuscript of the species of Puccinia occurring on this 
family of hosts for North American Flora. 
The number of species of Puccinia described from all parts of 
the world as occurring on members of the Carduaceae is very large, 
more than 300, and on account of the great variety of forms, and 
the close relationship and variability of the hosts which they inhabit, 
they offer a very interesting as well as difficult group for study by 
the uredinologist. In order to understand properly the forms 
occurring in North America, a study is being made so far as possible 
of all the described species. In order to bring together the present 
Knowledge of the species occurring on closely related hosts, the 
forms recorded on the different tribes of the Carduaceae are being 
taken up separately. 
Species of Puccinia are recorded on but three genera of the 
carduaceous tribe Vernoniae as limited by O. HorrMANN in ENGLER 
and PRANTL’s Die Pflanzenfamilien; these are Vernonia, Elephan- 
‘lopus, and Piptocarpha. The two latter genera harbor 2 species 
* Presented in part before the Botanical Society of America at Pittsburgh, January 
I, t918. Con tribution from the Botanical Department of the Purdue University 
Asiouiiaa Experiment Station. 
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