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FART IV. — VEGETABLE TAXONOMY. 



PART IV. 



VEGETABLE TAXONOMY. 



CHAPTER I. 



Value of Comparative Study. Vegetable taxonomy is 

 that department of botany which treats of classification, or the 

 arrangement of plants in groups or ranks according to resemb- 

 lances and differences. The study of plants in their relationships 

 to each other, distinguishing between differences which are 

 superficial and those which are deep-lying, and noting how even 

 the most diverse forms resemble each other fundamentally, is 

 not only an interesting exercise, but one of the most necessary 

 parts of botanical training. 



It is not possible, either, to understand any one plant thor- 

 oughly, or even any one plant-organ, except by comparative study. 

 We shall get, for example, a far more comprehensive view of the 

 nature and functions of the leaf, if we compare the different 

 modifications of it which occur on the Oak with those of the 

 Pea, the Pitcher-plant, the Venus' Fly-trap, and the Clematis, 

 than we should if we studied any one of them separately ; so 

 also we shall know more about the Rose plant if we study it in 

 comparison with the Indian Corn, the Pine, the Fern and the 

 Moss. 



Moreover, it is a matter of great interest and importance 

 to the student to obtain a clear conception of the vegetable 

 kingdom as a whole, as a great system of life. Of course, it is 

 not possible, even if it were desirable, within the limits of an 

 ordinary life-time, to become acquainted with all of the two 

 hundred thousand or more species of plants known to science ; 

 but to get some accurate knowledge of the principal types, and 

 of their relations to each other, to become thoroughly acquainted 

 with a few of the representative forms of each type, and to be 

 well acquainted with the flora of one's own neighborhood, is 



