Classification. 15 



of the science, but is only desirous of becoming acquainted 

 with the names and characters of such plants as he may meet 

 with in his rambles, this System offers facilities which are well 

 calculated to encourage. To determine the class and order by 

 counting the stamens and pistils, is generally a very simple 

 matter, and when this is done, the discovery of the genus and 

 species can be readily effected, with the aid of a Manual and a 

 little practice in examination. It is not too much to say, how- 

 ever, that this System is, after all, of no further use, taken by 

 itself, than merely to assist in finding out the name of an 

 unknown plant, and even in its application to this purpose it 

 possesses many imperfections. The number of pistils or of 

 stamens is often inconstant in any species, and varies even 

 among individuals of the same species, or even in the different 

 flowers of the same individual. This must of course lead to 

 great confusion, and every one who has experienced the fre- 

 quent difficulty of determining the name only of a plant by the 

 artificia>*hethod, must have become aware of the necessity in 

 such cases of applying to other principles for assistance. Then 

 it is that the necessity of means of discrimination not afforded 

 by the mere number or positions of stamens or pistils, becomes 

 apparent. For instance, the genus Polygonum, some members 

 of which are commonly known by the names of Bind- weed 

 or Knot-grass, is placed in the class Octandria and order 

 Trigynia. Now out of sixteen species of this genus, which are 

 found in the northern and middle states, nine only are Octan- 

 drous, and some of these vary, while of the remaining seven 

 species two are Pentandrous, three Hexandrous, and two Hep- 

 tandrous, and out of the whole sixteen at least ten are not pro- 

 perly Trigynous. Now, if without any previous knowledge of 

 these facts, the student should find a Polygonum which has 

 five, six, or seven stamens, he would at once look for it in the 

 class Pentandria or Hexandria or Heptandria. He finds 

 nothing like it, and must endure his perplexity and disappoint- 

 ment until some one who has perhaps passed through the same 

 difficulties shall tell him that his plant is a Polygonum. Should 

 he inquire how this happens, when it evidently belongs to a 

 different class, the only answer can be that it is so much like 

 the Polygonums that it cannot be separated from them, and 



