HOTANICAL APHORISMS; 163 
only to the genus Solanum, but to all those plants 
which stand under the same class and order. 
| § 148. 
GeENus is a number of plants which agree with 
one another in the structure of the flower and fruit, 
(§ 123). To distinguish the genera, we describe 
the flower and fruit, and such description is called 
the character: this is threefold, the natural, the fac- 
titious and essential, (character naturalis, factitius, et 
essentialis). 
The natural character, (character naturalis), 18 a 
description at large of the flower and fruit of a 
plant, made according to the rules of ‘Terminology, 
and serving for all the plants of a genus. Sucha 
description it is very difficult to make; but when 
once accomplished, it tends to the perpetual ascer- 
tainment of the whole. 
The essential character, (character essentialis), is 2 
very short description of the whole genus, which 
contains only the character which essentially distin- 
guishes it from every other. 
The factitious character, (character factitius), is an. 
essential chsracter, but where the number of the 
parts or some other circumstances, not of essential 
importance, are taken into it. 
The essential character is of great importance in 
the accurate investigation of a plant, and when it is 
obvious and distinct it throws great light on the 
knowledge of plants, ‘The factitious character is 
ni to be used when genera contain too great a 
L2 number 
