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 valid 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 earlier description. The second name 
then becomes asynonym. 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. 
Q 
