CHAPTER VI. 



CLASSIFICATION AND DISTRIBUTION. 



200. General Principles of Classification. — We may now 

 proceed to take a hasty survey of the Plant Kingdom, study- 

 ing here and there a selected example which must serve to 

 illustrate the structure of a considerable group. In such a 

 study of plants it is better to begin with the simpler and 

 more easily understood forms, and to pass from these to 

 those which are structurally more complex and whose func- 

 tions are correspondingly complicated. 



201. On account of the vast number of species of plants 

 — there are now known about 175,000, and the whole num- 

 ber in the world is probably more than twice as many — it 

 is necessary for us to group them in such a way as to bring 

 together those which resemble one another. In such group- 

 ing we take into consideration as many things as possible, 

 and those plants which are alike or similar in the greatest 

 number of particulars are considered to be more nearly re- 

 lated to each other than those with fewer points of resem- 

 blance. Moreover, it has been found that resemblances in 

 structure are of far greater importance than resemblances 

 in habits. Two plants, for example, may be parasitic in 

 habit, and yet their structural differences may be so great 

 as to warrant us in placing them in entirely different 

 groups. 



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