106 BOTANICAL SYSTEMS. [LESSON 33, 



571. The Natural System, as we receive it, and as to that portion 

 of it which is represented in the botany of our country, is laid before 

 the student in the Manual of the Botany of the Northern United States. 

 The orders, however, still require to be grouped, according to their 

 natural relationships, into a considerable number of great groups 

 (or alliances) ; but this cannot yet be done throughout in any easy 

 way. So we have merely arranged them somewhat after a custom- 

 ary order, and have given, in the Artificial Key, a Contrivance for 

 enabling the student easily to find the natural order of any plant. 

 This is a sort of 



572. Artificial Classification, The object of an artificial classifica- 

 tion is merely to furnish a convenient method of finding out the name 

 and place of a plant. It makes no attempt at arranging plants ac- 

 cording to their relationships, but serves as a kind of dictionary. It 

 distributes plants according to some one peculiarity or set of pecu- 

 liarities (just as a dictionary distributes words according to their 

 first letters), disregarding all other considerations. 



573. At present we need an artificial classification in Botany 

 only as a Key to the Natural Orders, as an aid in referring an 

 unknown plant to its proper family ; and for this it is very needful to 

 the student. Formerly, when the orders themselves were not clearly 

 made out, an artificial classification was required to lead the student 

 down to the genus. Two such classifications were long in vogue. 

 First, that of Tournefort, founded mainly on the leaves of the fiower, 

 the calyx and corolla : this was the prevalent system throughout the 

 first half of the eighteenth century ; but it has long since gone by. 

 It was succeeded by the well-known artificial system of Linnaeus, 

 which has been used until lately ; and which it is still worth while 

 to give some account of. 



574. The Artificial System Of LinnaiUS was founded on the stamens 

 and pistils. It consists of twenty-four classes, and of a variable 

 number of orders, which were to take the place temporarily of the 

 natural classes and orders ; the genera being the same under all 

 classifications. 



paper at least, a strictly definite limitation of genera, of tribes, and of orders, 

 although observation shows so much blending here and there of natural groups, 

 sufficiently distinct on the whole, as to warrant us in assuming the likelihood 

 that the Creator's plan is one of gradation, not of definite limitation, even perhapi 

 vO the species themselves. 



