296 CONCERNING NOMENCLATURE. 



name to a plant, but since he was the first to recognise 

 the utility of a binomial system of nomenclature, and 

 to establish such a system upon a sound basis, botanists 

 have unanimously agreed to begin their nomenclature 

 with the publication of his " Species Plantarum " in 1753. 

 In this work was included every species of plant known 

 to Linnaeus and the names he there gave them are the 

 ones botanists are supposed to use. One thing, how- 

 ever, has conspired to make a large number of changes 

 in these names not only permissible but necessary. 

 This is the broad view of genera taken by Linnaeus. 

 He placed all the ferns in a very small number of genera. 

 In his genus Poly podium, for example, were placed species 

 that are now found in Cystopteris, Aspidium, PolysticJium 

 and Phegopteris. Subsequent study convinced botanists 

 that many of these species were distinct enough to be 

 placed in separate genera and this was accordingly done, 

 the generic name, of course, having to be changed in 

 the process. Unfortunately for nomenclature, these 

 botanists, working remote from one another, frequently 

 made different genera for the same species without 

 knowing it. Thus the rusty Woodsia was known to 

 Linnaeus as Acrostic/turn Ilvense, to Swartz as Polypodium 

 Ilvense, to Michaux as Nephrodium rufidulum and to 

 Willdenow as Aspidium rufidulum. Since we are sup- 

 posed to always use the earliest name, it often becomes 

 a nice question to decide which is first. Not only this, 

 but different authors sometimes gave the same name to 

 different plants unaware that it had been used before. 

 Under these circumstances it has become necessary in 

 exact science to add the name of the author to each com- 

 bination of generic and specific names to show which 

 species is meant. 



