134 
USE OF BOTANICAL NABIES. 
necessary to resort to this instrument, in order to establish the natural 
•relations of plants.* 
Having considered the meaning of individual^ species, genus, nnd 
family, and of the characteristics by which these are grouped toge- 
ther, let us take a general view of the subject. It is evident, b> the 
formation of species, genera, and families, that every species should 
offer the essential characters of the family and genus to whicn it be- 
longs ; while the marks which distinguish this species from anothei 
species of its genus, will be such as do not belong to the whole ge- 
nus or family. The different genera in families are also distinguished 
by characters which do not belong to the whole family ; every indi- 
vidual, then, will possess its specijic character, its generic charixcter, 
and its family character. 
The specific character is less important than the generic, as it is 
mostly founded on the characters of the organs of vegetation, which 
we have seen are isolated, and less important than the coexistent 
characters. We often find, in the analysis of plants, a great dirliculty 
in determining their species, from the want of definite marks of dis- 
tinction. 
Generic characters are mostly of the coexistent kind, and are 
more valuable than the specific characters. The distinctions of gen- 
era are usually much more apparent than those of species ; as a 
rose can be more easily distinguished from a pink, than one species 
of rose from another species. 
Families are grouped together by marks of resemblance found m 
genera. These family characters are, of all others, the most impor- 
tant. In the artificial classes and orders we depend on what we have 
before termed factitious characters. In species, genera, and fami- 
nes, the essential characters are also natural characters. 
LECTURE XXIII. 
USE OF BOTANICAL NAMES ARTIFICIAL CLASSES AND ORDERS CONSIDERED IN 
GROUPS — CLASSES MONANDRIA AND DIANDRIA. 
You have been taught the principles on which the Linnsean sys- 
tem is founded ; we shaH now examine each class separately, with 
the orders it contains, and the most remarkable plants and natural 
families which we shall meet with in our progress through this system. 
We have observed, that this appears to be the best method yet 
discovered of classing new plants, and of ascertaining the botanical 
names of those which are already known by common names. If, 
in all countries, the common names were alike, there would be no 
need of any other; but the names of plants vary in different lan- 
guages as much as other terms. Even in the same country, and 
often in the same neighbourhood, the common names of plants are 
different ; but botanical names are the same, in ail ages and coun- 
♦ The foregoing rules and observations respecting characters for classification, are 
chiefly translateafrom Mirbel's " Elemens de Botanique." 
General view of the subject of classification— Which is the more important, the spe- 
cific or generic character 7 — Why are generic characters most valuable ?— How are 
families grouped together On what do artificial orders depend?— What are the es- 
wntial characters in species, genera, and families ?— Why are not the common names 
>t plants «ufl5«itent for all purposes'? 
