NORTH AMERICAN RUSTS ON CYPERUS 

 AND ELEOCHARIS' 



Frank D. Kern 



The rusts inhabiting the species of the genus Car ex have re- 

 ceived considerable attention from both taxonomic and cultural 

 viewpoints. The most recent accounts recognize in North Amer- 

 ica twenty-three species of Carex rusts, four with i-celled telio- 

 spores (Uromyces or Nigredo type)^ and nineteen with 2-celled 

 teliospores (Puccinia or Dicacoma type).^ The rusts of other 

 sedges have been studied much less carefully. Although Cyperus 

 and Eleocharis are smaller and less variable genera than Car ex 

 it has not seemed reasonable that their rust flora should be so 

 much more meager in North America as to consist of but three 

 species on the two genera, yet this has been the generally accepted 

 situation up to the present time. All specimens of rust on Cyperus 

 have been called Puccinia Cyperi or P. canaliciilata, these names 

 being considered synonymous, while on Eleocharis i -celled telio- 

 sporic forms have been called Uromyces Eleocharidis, and 2-celled 

 forms Puccinia Eleocharidis. 



Cyperus is a genus of about 600 species with a considerable 

 distribution in the tropics whereas the genus Carex has something 

 over 1,000 species chiefly distributed in temperate regions. 

 Eleocharis is a much smaller genus. It is made up of about 140 

 species, rather widely distributed. 



With the facts in mind as to the relative importance, of the 

 genera Cyperus and Eleocharis it was anticipated that a careful 

 study of their rusts would reveal the presence of some additional 



1 Read before the joint session of the Botanical Society of America and 

 American Phytopathological Society, Baltimore meeting, Dec. 27, 1918. Con- 

 tribution from the Department of Botany, Purdue University Agricultural 

 Experiment Station, and from the Department of Botany, The Pennsylvania 

 State College, No. 15. 



2 North American Flora 7: 234-236. 1912. 



3 Mycologia g: 205-238. 1917. 



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