PART II 



THE REPRODUCTIVE ORGANS 



CHAPTER XII 



BIOLOGY OF THE FLOWER. DICOTYLEDONS 



I. Pollination of Simple Flowers by Wind and Insects 



In the study of buds, corms, and bulbs, we have become 

 familiar with the facts that shoots are frequently condensed ; 

 that the internodes, instead of elongating, remain un- 

 developed ; and that, in consequence, a number of leaves 

 spring close together from the short axis. Some of the 

 leaves arise singly and are arranged in a close spiral, while 

 others stand two at a level, in crossed pairs. 



The flower a condensed and modified shoot. In our exam- 

 ination of the Stock flower we found something very similar, 

 viz. a condensed or dwarf shoot, with a tendency for the 

 flower-leaves to arise close together in crossed pairs. This 

 condensation is characteristic of flowers, and it is interesting 

 to note how frequently flowers arise on dwarf, leafy shoots, 

 or spurs, as in many fruit-trees. This shortening of the 

 axis, together with the great modification that has taken 

 place in the size, shape, colour, and function of its parts, 

 distinguishes a typical flower from any other part of the 

 plant. 



Flowers, however, have not arisen in this simple way 

 from a leafy shoot. It is more probable that stamens and 



