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The Genus Puccinia. 

 J. C. Arthur. 



The present paper Is a continuation of two previous attempts to bring 

 to the notice of this society something of the efforts that are being made 

 to devise a worlvable method that will eventually lead to a stable nomen- 

 clature for plants. The necessity for having one authoritative name for 

 each species and genus of plants is conceded by all botanists. The 

 methods proposed for arriving at this desirable state are various. It is 

 evident that nomenclature will never become stable if left to itself, that 

 is, to the judgment of the individual. There must be rules of procedure 

 which most botanists, if not all, will feel bound to respect. 



The wise formulation of such rules and the impress of authority, 

 which they must necessarily bear, are difficult to secure. Were there an 

 international organization of recognized competency to take up the matter, 

 the way would seem easy. In the absence of such a body, suggestions 

 and attempts must be expected from various sources, which may finally 

 crystallize into a form which the botanical world at large will accept. 



American botanists, acting through the American Association for the 

 Advancement of Science, promulgated the Rochester-Madison rules of 

 nomenclature in 1892-93. These rules, after the test of a decade, have 

 been somewhat modified and extended, and today represent the most care- 

 fully considered and most practical scheme for securing uniformity of 

 procedure in naming plants that has yet been brought forward. What- 

 ever may be thought of these rules, or of any other, it is certainly the 

 part of wisdom to test their applicability, and lend a hand to their im- 

 provement. 



In order to illustrate the American rules I propose to take the very 

 interesting case of the genus Puccinia. As the name is generally used it 

 embraces about one thousand species of plant rusts, which are character- 

 ized by having free, two-celled telentospores. In my paper* of four years 

 ago I pointed out, that according to the Kuntzean rules of nomenclature 

 this generic name should be transferred to the cedar apple rusts, to re- 

 place Gymnosporangium, a name that has been in use since 1805. In my 

 second paper,t presented two years later, I showed that if we accept the 



'■'Indiana plant rusts, listed in accordance with latest nomenclature. Prcjceedings 

 Indiana Academy of Science for 1898:174-186. 



t Generic nomenclature of cedar apples. Proceedings Indiana Academy of Science 

 for 1900:131-136. 



6— Academy of Science. 



