236 EVOLUTION 



the origin of the flower, which all agree in 

 regarding as a shoot modified for reproduction. 

 But it is also shortened, as compared with 

 a vegetative shoot; then why ? By natural 

 selection from two other alternative variations? 

 one like the vegetative shoot, and the other 

 lengthened farther still ? These are imagin- 

 able as forms; there is no morphological 

 absurdity about them : yet we may be fairly 

 sure they never existed at all, and so have 

 not been selected. How so ? They are 

 excluded by the physiological explanation 

 of inevitable shortening; since the organic 

 expenses of the onset of the reproductive 

 function necessarily checks the vegetative 

 ones. 



Similarly for flower groupings, the " forms 

 of inflorescence." The simplest form is the 

 long flowery stem, each flower with its own 

 stalk, like the foxglove spire; but such fine 

 " racemes " are comparatively uncommon. 

 Often the flower-stalks are arrested, and we 

 have the " spike," as in the mullein, golden rod; 

 or again it may be the main stem which stops 

 short, leaving the minor stalks to grow and 

 separate the flowers, as in the " umbel " of 

 cowslip (and even primrose), of ivy and of the 

 parsley and hemlock tribe without number. 

 But in one great order, and that significantly 



