NOMENCLATURE 257 



VALID NAMES AND SYNONYMS 



281. The student is often disconcerted when he finds 

 that a species has more than one name. It should be under- 

 stood that a given species, as viewed by a given botanist, 

 has but one vaUd name, all other names being synonyms. 

 A genus bears the name assigned to it by the botanist who 

 first indicated or described it. (By common consent names 

 dating publication prior to 1753 are excluded.) A later 

 botanist may describe the same genus as new, not being 

 acquainted with the earUer description. The second name 

 then becomes a synonym. Sometimes an author describes a 

 new genus and assigns to it a name which has already been 

 used for an earlier genus. Such a name is a homonym, 

 and can not be accepted as valid, hence the genus must 

 receive a new name. A botanist may divide a genus of an 

 earlier author into two or more distinct genera (generic 

 concepts being opinions), in which case he retains the 

 original generic name for one of the parts and assigns new 

 names to the other parts. It is clear, then, that the same 

 species might have two valid names according to the vary- 

 ing concepts of two botanists. Barnyard-grass would be 

 called Panicum Crus-galli by one botanist who considered 

 Echinochloa to be a section of Panicum, and Echinochloa 

 Crus-galli by another who considered the group Echino- 

 chloa to constitute a distinct genus. 



Specific names are governed by the same rule, that is 

 priority. The earliest name is used if there is no reason 

 for rejecting it. In transferring a species from one genus 

 to another the original specific name is retained unless 

 there is already in the second genus a species by that 

 name, in which case the transferred species receives a 

 new name. 



