PART IV. 



CLASSIFICATION AND SPECIAL BOTANY 

 OF FARM CROPS. 



CHAPTER XXIV. 



THE CLASSIFICATION OF PLANTS. 



I. Systematic or Classificatory Botany is concerned with the 

 naming, describing and arranging of plants into groups. 



Various systems of classification have been proposed from 

 time to time, the one which has superseded all others being the 

 so-called Natural System. Underlying it is the assumption that 

 all the different kinds 'of plants on the face of the earth have 

 been derived by natural descent from a few ancient ancestors, 

 and the object of this system is the arrangement of plants into 

 groups according to their affinity or blood-relationship. 



The evolutionary history and genetic affinity of plants can 

 never be known accurately, and there are no universal rules by 

 means of which the relationship of organisms can be determined 

 with certainty. However, in forming the groups into which the 

 Vegetable Kingdom is divided, botanists endeavour to take into 

 consideration as many peculiarities or characters of the plants as 

 possible, and place together only those which agree in a number 

 of characters : it is reasonably contended that by this method 

 plants which are related to each other by descent are likely to be 

 brought together. 



2. The terms employed to denote the different groups are 

 indicated below. 



