CHAPTEE XVII. 



True Nature of Floral Organs ; Details of their 

 Structure. 



187. The Flower a Shortened and Greatly Modified Branch. 



— In Chapter IX, the leaf- 

 bud was explained as being 

 an undeveloped branch, 

 "which in its growth would 

 develop into a real branch 

 (or a prolongation of the 

 main stem). Now since 

 flower-buds appear regu- 

 larly either in the axils of 

 leaves or as terminal buds, 

 there is reason to regard 

 them as of similar nature 

 to leaf-buds. This would 

 imply that the receptacle 

 corresponds to the axis of 

 the bud shown in Fig. 60, 

 and that the parts of the 

 flower correspond to 

 leaves. There is plenty of 

 evidence that this is really 

 true. Sepals frequently 

 look very much like leaves, 

 and in many cactuses the 

 bracts about the flower are 

 so sepal-like that it is im- 

 possible to tell where the 

 The same thing is true of 



E F G 



FiQ. 136. — Transitions from Petals to Sta- 

 mens in White Water-Lily. 

 E, P, G, H, various steps between petal 

 and stamen. 



bracts end and the sepals begin. 



