CHAPTER IV 



THE ANATOMY OF THE FLOWER 

 AND FRUIT 



FUNCTIONALLY, the flower is an organ concerned with the 

 development of the structures that lead to gametic reproduction. 

 On this basis, the statement of Goebel (3) that a flower is "a shoot 

 beset with sporophylls" is in accord with the floral function, 

 since the stamens and carpels produce microspores and megaspores 

 from which the gametophytic structures arise. These, in turn, 

 produce gametes, gametic union ensues, and the resultant zygote 

 develops as a new sporophytic generation. It is evident from this 

 that the flower is a sporophytic structure, and that it is a mis- 

 conception to refer to the stamens and carpels as organs of gametic 

 or sexual reproduction. 



Anatomically, the flower is a shoot. On this basis, the floral 

 axis is not unlike a vegetative one, as described in the preceding 

 chapter, which gives rise to successive leaf primordia from a ter- 

 minal meristem. The difference is not fundamentally in the man- 

 ner of origin of the foliar and floral parts respectively; but, rather, 

 in the character and function of the structures. 



Floral Parts. — The typical, perfect flower of the angiosperms 

 has four types of floral leaves, sepals, petals, stamens, and carpels, 

 which are diverged from the receptacle or torus. The two first 

 named do not possess sporangia, and constitute the floral envelope 

 or perianth; the other two, stamens and carpels, normally bear 

 functional sporangia. In addition to these parts various types of 

 bracts may be associated with an individual flower, as in many of 

 the Rosaceae. The differences which distinguish the many floral 

 types are quantitative rather than qualitative variations, since the 

 same basic structures may be present in any given flower; but 

 their size, number, and degree or extent of development may vary 

 widely. There may be qualitative modification of such structures 

 as carpels and stamens; but, this is far less common than quantita- 



88 



