NORTH AMERICAN SPECIES OF ALLODUS^ 



C. R. Orton 



Pennsylvania State College 



Introduction 



The genus Allodus Arth. of the Uredinales is a group of para- 

 sitic fungi having pleomorphic spore-forms and so far as is known 

 all species of the genus are autoecious. 



The rnost conspicuous character of the genus is the frequent 

 close association of aecia and telia on the same plant parts and 

 the absence of distinct uredinia. These characters are identical 

 with those of Uromycopsis (Schrot.) Arth., a genus exactly parallel 

 with Allodus. 



The failure to produce uredinia makes the aecial stage of 

 particular interest from the taxonomic and cytologic standpoint. 

 The cultural studies which have been made with species of this 

 genus are substantiated by the taxonomic studies. 



The descriptive matter herein given is as brief as possible 

 without leaving out essentials. These descriptions together with 

 the analytic key should enable the collector and mycologist to 

 determine the species belonging to this genus, provided the speci- 

 mens bear more than one stage of the rust. The presence of 

 uredinia {i. e., uredinial sori, not necessarily urediniospores) at 

 once throws a rust out of this genus while the grouping of the telia 

 is quite distinct from that in the short cycle genus Dasyspora. 



1 Contributions from the Department of Botany, Pennsylvania State College, No. 6. 



This paper is the result of investigations started in the Botanical Laboratory of 

 the Purdue University Agricultural Experiment Station while the author was connected 

 with that institution. Upon his removal to The Pennsylvania State College that part 

 of the Arthur Herbarium dealing with the subject matter was very generously loaned 

 for the continuation of this study. The writer is indebted to the officers and botanical 

 staffs of these institutions, who have so generously aided him. 



To Dr. J. C. Arthur, who has aided the writer in many ways, especial acknowledg- 

 ment is made. To Dr. F. D. Kern the writer is greatly indebted for advice along 

 special lines. Acknowledgment is made also to Dr. H. D. House for the determination 

 of host plants of the genus Ipomoea. 



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