142 THE FLOWER. [CH. XI 



other genera constitute a Natural Order, the Legumi- 

 nosce. 



In classifying, botanists are guided chiefly by the 

 structure of the flowers, by the form, number and 

 position of the petals, and of the other floral organs, 

 so that the morphology of the flower comes to be the 

 key to the science of systematic or classificatory botany. 

 And it should be noted that in classifying plants we are 

 not simply satisfying the instinct which leads us to sort 

 our possessions into like and unlike. The classification of 

 living things has an interest which does not attach to the 

 arrangement of artificial objects such as postage-stamps. 

 Living things are not merely placed in groups as an 

 expression of resemblance, they are classed in natural 

 groups, that is to say they are ranged according to blood- 

 relationship. Thus in the case of the Ranunculaceae it is 

 believed that all the genera are descended from a single 

 ancient plant, and a wide field for speculation is open to 

 us, as to how and why the primaeval Ranunculus has left 

 such varied descendants as the Larkspur, the Marsh Mari- 

 gold, &c. 



The flower. 



The flower is essentially a shoot or axis bearing leaves 

 on which the reproductive elements are produced. The 

 proof that the petals and other floral organs are morpho- 

 logically of the rank of leaves cannot here be given in any 

 detail. A few of the arguments in favour of this belief 

 may however be sketched. The development of the parts 

 of the flower as superficial outgrowths from the growing 



