GENERAL STRUCTURE 



273 



stigma. Beneath the stigma there is an elongated and 

 usually slender part called the style ; the function of the style 

 appears to be to get the stigma in a position which is favor- 

 able for receiving pollen. Some pistils have no style, as 

 in the water Hly. (See Figure 108, page 287.) 



The base of the pistil is an enlarged part called the 

 ovary or seed vessel. (Seed vessel is a preferable name 

 for this structure for the 

 reason that the ovary of an- 

 imals is an entirely different 

 structure from the ovary of 

 plants. But this structure 

 was called an ovary before its 

 real nature was understood 

 and that name is still gener- 

 ally given to it.) The ovary 

 is that part of the pistil which 

 develops into the fruit and 

 contains the seeds. 



Sepals, petals, and stamens 

 are all, as has been noted, 

 leaves as to origin ; they arise 

 as leaves arise; when they 

 are very young they look ex- 

 actly like very young leaves ; 

 they are sometimes referred 

 to as " modified leaves." 

 Thus the calyx, the corolla, and the androecium may all be 

 regarded as sets or whorls of modified leaves. Similarly 

 the pistil may be regarded as a modified set of leaves, but 

 since it is usually a single structure, the parts which com- 

 pose it are not so well known or so evident as the parts of 



Fig. gj. — Lengthwise section through 

 a flower, showing the relation of parts. 

 See context. 



