Orton: Correlation between Puccinia and Uromyces 195 



author there were three species now referable to the genus Puc- 

 cinia included under that genus along with species representing 

 at least three other genera, and under Nigredo, a name which he 

 established as a subgenus of Uredo, there were several species 

 which would now be referred to Uromyces. 



The principal workers Avho followed Persoon were Schumacher 

 in 1803, Willdenow in 1804, and DeCandolle in 1805. The last 

 author made a slight variation from Persoon's classification in his 

 admirable systematic work on the French flora.* He divided the 

 genus Puccinia into three sections, the first of which included 

 several species of Phragmidium. The second section contained 

 13 species, the majority of which are referable to Puccinia as 

 now used. Under the third section, which he characterized as 

 being similar to Puccinia but having one-celled spores, six species 

 were listed all of which are now referred to Uromyces. 



After DeCandolle came Link, who in 1809^ established the 

 genus Caeoma corresponding to Uredo of Persoon. It was 

 divided into five sub-genera. Under the sub-genus Caeomurus 

 he placed DeCandolle's third section of Puccinia with one-celled 

 spores, now properly referred to Uromyces. In 1816^ Link sepa- 

 rated the genus Phragmidium from Puccinia under which it had 

 been previously included and left under Puccinia several species 

 now properly referred to this genus. In this same work Caeoma 

 was changed to Hypodermium and Caeomurus to Uromyces but 

 their generic relation to each other remained as in 1809. In 

 1825^ he published his third important contribution, in which the 

 rusts were classified under several genera which included Caeoma, 

 Puccinia, Triphragmium, Phragmidium, Podisoma, and Gymno- 

 sporangium. There were 48 species listed under Puccinia, prac- 

 tically all of which are now referable to that genus. Caeoma was 

 divided into four sub-genera, namely: Uredo, Aecidium, Cerati- 

 tium and Peridermium. The first contained 113 species many 

 of which were probably in the uredinial stage. There appears to 

 be no disposition of species belonging to Uromyces except under 

 this sub-genus. 



* Flora Francaise 2: 218-236. 1805. 



^ Ges. Nat. Freunde Berlin Mag. 3: 6. 1809. 



® Ges. Nat. Freunde Berlin Mag. 7: 28-30. 1816. 



'Willd. Sp. Plant. 6=^. 1825. 



