112 SYSTEMATIC BOTANY. 



one plant of the genus Trifolium will convey intelligence, to a certain extent 

 concerning eveiy other plant belonging to its 150 species. 



335. Thus the whole vegetable kingdom is grouped into species, and the spe- 

 cies themselves into genera. But natural affinities do not stop here. The genera 

 are still too numerous for the purpose of clear and systematic study. The natu- 

 ralist would therefore generalize still further, and reduce the genera to still fewer 

 and larger tribes or groups. Accordingly he finds, on comparing the genera with 

 each other, that they still possess some characters in common, although, perhaps, 

 of a more general nature than those which distinguish them among each other. 

 These general characters, therefore, serve to associate the genera into a sys- 

 tematic arrangement of Classes and Orders. 



336. There are two independent and widely different methods 

 of classifying the genera, which have generally been approved, 

 namely, the Artificial System of Linnaeus, and the Natural Sys- 

 tem of Jussieu. The former has for its basis those characters 

 which are derived from the organs of fructification, leaving all 

 other natural affinities out of view. The latter, on the contrary, 

 is founded upon all those natural affinities and resemblances of 

 plants, by which Nature herself has distinguished them into 

 groups and families. 



337. In regard to the relative merit of these two systems, there is now no longer 

 room for comparison. That of Linnaeus is beautiful and ingenious, and, in the 

 early stages of science, furnished the readiest means for determining the names 

 of plants ; but this must be regarded as its principal use. Indeed, its author him- 

 self did not design it. for any higher end, or claim for it any higher merit. 



338. But, in acquiring a thorough and accurate knowledge of the vegetable 

 kingdom, the Natural System is not only the best, but it is the only method which 

 can be relied upon for this purpose. The obscurity and misconceptions which 

 formerly embarrassed the science of the vegetable structure, so as to render this 

 system unavailable, have now been so far removed by the labors of De Candolle 

 and Lindley, in Europe, and of Drs. Torrey and Gray, of our own country, that it 

 is brought generally within tbe scope of the ordinary mind, and shown to be 

 founded in true philosophy. Accordingly, it is now generally adopted. 



o39. It was long supposed that no other arrangement than that of Linnaeus 

 could be practically useful in analysis, and consequently almost every local flora 

 retains this arrangement even to this day. But the use of such an arrangement is 

 objectionable, since it severs true affinities, confounds natural distinctions, often 

 dispersing widely apart even the species of tbe same genus, thus preoccupying the 

 young mind with views contrary to true science. In this work this system is 

 wholly laid aside, and an attempt is made to prepare an analytical synopsis oi the 

 Flora, founded upon the Natural System, to some extent, indeed, artificial, yet 

 exhibiting no form save that of the true system. 



