SYSTEMS OF BOTANICAL CLASSIFICATION. 



181 



We have now stated the principles of the 

 sexual system, and presented a sketch of its 

 twenty-four classes and numerous orders, such 

 as they were established by Linnaeus. In ex- 

 amining this system, one is strack by its ex- 

 treme simplicity, and the ease with which the 

 name of a plant may be discovered by means of 

 it. The classes, in fact, are, for the most part, 

 precisely limited and defined, especially those 

 which have the stamina in determinate number. 

 Not only does this system contain all the plants 

 already known, but it is also capable of com- 

 prehending all that may yet be discovered. In 

 consequence of its possessing these advantages, 

 it was generally adopted at the period of its 

 first publication. 



But it must be admitted, that it labours under 

 more than one serious disadvantage. It is not 

 always easy to determine the precise class to 

 which a plant ought to be refen-ed. Thus the 

 i-ue {Ruta graveolens) has almost all its flowers 

 furnished with eight stamina, there being only 

 a single flower in the centre of each of its groups 

 that presents ten. The beginner, in this case, 

 would experience some embarrassment, and 

 might be induced to place the plant in question 

 in the eighth class of the system, Octamdria, 

 although Linnseus referred it to Decandria, as 

 lie considered the flower with ten stamens as the 

 most perfect. 



Dodecandria, in like manner, is not very 

 strictly characterized. It contains all the plants 

 which have from twelve to twenty stamina; but 

 the agrimony, which is referred to it, has often 

 more than twenty. 



Certain labiate or personatae which belong to 

 Didynamia, have their four stamina of equal 

 length, and the irregularity of the corolla is, in 

 many cases, hardly perceptible. 



It is extremely difiicult to determine with cer- 

 tainty the orders to which many plants belong- 

 ing to Syngenesia should be referred. Besides, 

 the intermixture of male flowers, female flowers, 

 and hermaphrodite flowers, throws several of 

 them into Dimcia and Polygamia. The sixth 

 of these orders Polygamia Monogamia, contains 

 plants which have no afl&nity to the compositse, 

 such as the genera Viola, Lobelia, Impatiens. 



Polygamia, the twenty-third class, is a con- 

 fased mixture of plants, which almost all belong 

 to some of the other classes. 



If we now examine the plants brought to- 

 gether under each of these classes, we find that 

 very frequently the natural affinities that have 

 long been established are entirely disregarded. 

 Thus one of the most natural families, the 

 Gramineje, is scattered through the classes Morir- 

 andria, Diandria, Triandria, Hexandria, Mon- 

 <ecia, Dimcia, and Polygamia. The labiatas are 

 partly placed in Diatidria, partly in Didynamia. 

 It is the same with many other families equally 



natural. But as the classification proposed by 

 Linnaeus is a system, that is, a methodical, but 

 purely artificial arrangement, intended solely 

 for facilitating the discovery of the name of a 

 plant which one may be desirous of Icnowing, 

 it would not be just to blame it for having thus 

 separated plants which bear a great resemblance 

 and affinity to each other. But the Linnaean 

 system is not the one which is to be studied 

 when the object is to obtain a knowledge of the 

 mutual relations of plants, although, of aU the 

 artificial systems, it is unquestionably that 

 which enables one to find the name of a plant 

 with most ease. 



The system of Jussieu, or The method of 

 Natubai Families, differs essentially in itscourse 

 and characters from the systems of Toumeforte 

 and Linnaeus, which we have already explained. 

 In it the divisions are not founded upon the 

 consideration of a single organ, but are derived 

 from characters presented by all the parts of 

 plants. Accordingly, the plants which are thus 

 brought together are disposed in such a manner 

 that they have a greater affinity to that which 

 immediately precedes or follows them than to 

 any other. 



This classification is therefore superior to those 

 which preceded it, in so far as it presents general 

 and philosophical ideas respecting the produc- 

 tions of the vegetable kingdom. It does not 

 consider objects separately, but collects and ar- 

 ranges them into groups or families, according 

 to the greatest number of common characters 

 which they possess. 



We find that nature, in impressing upon the 

 external form of certain plants a peculiar char- 

 acter bearing relation to their internal organiza- 

 tion, seems to have indicated to a certain extent, 

 the affinities which exist among vegetable pro- 

 ductions. In fact, there are many plants which 

 bear so great a resemblance to each other in the 

 structure and conformation of their parts, that 

 this similarity has at all times been perceived, 

 and these different plants have been considered 

 as in some measure belonging to the same family. 



Thus the Gramineae, Labiatse, Cruciferae, and 

 Synanthereae, have always been kept together 

 whenever the characters of affinity and mutual 

 resemblance have not been sacrificed to the prin- 

 ciples of an artificial system. 



Accordingly, when botanists began to bring 

 together plants into families, that is, into groups 

 or series of genera, resembling each other in the 

 greater number of characters, they had only to 

 imitate nature, which had, as it were, created 

 types of essentially natural families, as if to 

 sei-ve as models. Thus the leguminosae, cruci- 

 ferae, gi-amineae, umbelliferse, labiatce, &c., stood 

 forth to the view as so many exainjjles which 

 were to be imitated. 



But as all plants hare not, like those just 



