CHAPTER XVI 



TRUE NATURE OF FLORAL ORGANS; DETAILS OF 

 , THEIR STRUCTURE; FERTILIZATION 



221. The Flower a Shortened and greatly Modified 

 Branch. — In Chapter VIII, 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 regularly 



Fig. 158. — Transition from Bracts to Sepals in a Cactus Flower. 



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. 86, and that the parts of 

 the flower correspond to leaves. There is plenty of evi- 

 dence that this is really true. Sepals frequently look 

 very much like leaves, and in many cacti the bracts 



208 



