PART 11. 



SYSTEMATIC BOTANY 



CLASSIFICATION OF PLANTS. 



In order to aid us in acquiring a knowledge of the 

 properties and general characteristics of those plants 

 which fall under our observation, some mode of classifi- 

 cation is necessary. The advantages of systematic ar- 

 rangement are the same here as in other sciences. It 

 aids us in prosecuting our own researches, and in becom- 

 ing familiar with a more widely extended circle of vege- 

 tation ; and it is almost indispensable to us, in availing 

 ourselves of the investigations of others. It also opens 

 to us a new and most important branch of the subject, in 

 the study of the various relationships of plants, and of 

 their relative structure and development. 



There are two kinds of classification in use, one 

 founded on artificial distinctions, and forming a kind 

 of dictionary of plants, the other depending upon 

 NATURAL characters, or those derived from the plants 

 themselves, and truly representing their affinities. The 

 only advantage which an artificial method can pos- 

 sess, must be a greater simplicity and capability of being 

 understood and applied. It does not, of itself, in any 

 way increase our knowledge of plants, while it is a great 

 obstacle in the way of all attempts to study and under- 

 stand their mutual relations and affinities. A Natural 

 method, on the contrary, while it can be made as simple 

 as any to those who are acquainted with the physiologi- 

 cal structure of plants, has this great advantage, that a 

 comprehension of the mere system itself, increases our 

 practical knowledge of plants, and especially of the vari- 

 ous relations of their different tribes ; and thus gives us 

 much better and clearer conceptions of the vegetable crea- 

 tion. Indeed, without such a system, we could hardly 



form any idea of it, viewed as a whole ; or, at best, but a 

 very imperfect and unsatisfactory one. 



A Natural Method, then, merely recognizes, as the 

 foundations of its classification, certain fundamental dis- 

 tinctions and affinities observed in the plants themselves. 

 It is my intention here to explain the principles upon 

 which all natural methods are formed, and then go on to 

 describe particularly the chief divisions of the system of 

 Jussieu, which, with amendments and additions by later 

 Botanists, is now almost universally adopted. 



The most important, and strictly natural arrange- 

 ment, is that which distributes individual plants into 

 Species, and these species again into Genera. The 

 principles upon wiich these distinctions rest are so sim- 

 ple, and so obvious, that they are almost universally 

 recognized, even by those unacquainted with the science 

 itself. Hence they form the basis of all subsequent 

 classifications ; nor, since Botany has been studied 

 scientifically, has there been any classification, however 

 artificial, which has not recognized their existence. 



A Species is a general name applied to all those in- 

 dividual plants which have so near and 'perfect a 

 resemblance, that they seem formed, in all their parts, 

 closely after the same type, or model. They must be 

 such as could have descended from a common stock ; or, 

 what is the same thing, such as might be produced by 

 the seed of any one of the individuals. Thus, if we go 

 into a field of red Clover, we instinctively recognize the 

 difierent individuals of the Clover, as belonging to the 

 same species, because they are so obviously formed after 

 the same model. We see at once that all these might 

 have descended from a single individual, or that we 

 might take the seed of one of them, and in time produce 



