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Botanical Gazette. 



Vol. VIII. OCTOBER, 1883. No. 10. 



Enumeration of the Peronosporese of the United States.* 



BY W. G. FARLOW. 



In 1876 I published in the Bulletin of the Bussey Institution 

 an account of the species of Peronospora and Oystopus, known at 

 the time to occur in the United States, and the total number 

 given was only ten. Having occasion recently to review the 

 species of those genera in my collection, it occurred to me that, 

 considering how many species have been added to our flora since 

 1876, it would be desirable to prepare a new list which should 

 be as complete as the materials in my possession would permit, 

 and, as the descriptions of some of the species are not accessible 

 to many persons in this country who desire to study the subject, 

 to add descriptions of all our species. The material examined 

 has been specimens which I have collected myself and specimens 

 in my herbarium, for which I am indebted to the kindness of 

 several correspondents. In the arrangement of the synonymy I 

 have endeavored to give the synonyms which are likely to be 

 most frequently seen in text-books and agricultural treatises, and 

 those who care for a detailed account of the synonymy of the 

 more common species are referred to DeBary's original paper. 

 Frequent references are made to American botanical works where 

 our native species are mentioned ; and where American speci- 

 mens have been distributed in published exsiccati I have given 

 the numbers, when they are known to me, without going so far 

 as to quote European specimens of species which occur also in 

 this country. The additions to our Peronosporece are mainly 

 scattered through the reports of the New York State Botanist, 

 Mr. C. H. Peck, and in the Bulletin of the Bussey Institution, 

 and Ellis's North American Fungi Century III. contains a num- 



* This paper was presented at the meeting of the Society for the Promotion 

 of Agricultural Science at Minneapolis, Aug. 14, 1883, and is now printed with 

 the permission of the President, Prof. W. J. Beale. 



