140 



BOTANY. 



lect some flower-head in which the parts are well devel- 

 oped, as the marigold, thistle, or dandelion. Fig. 416 

 shows a thistle-head, with 

 lines pointing to its princi- Florets. 



pal divisions. 



Fig. 417 represents a 

 marigold, in which the same 

 parts are shown. In Fig. 

 418 we look down upon the 



top of the flower-head, 

 and observe that it pre- 

 sents unlikeness of as- 

 pect, which is still more 

 FIG. 418. plainly shown in section 



in Fig. 419. 



The parts pointed out in these pictures may be thus 

 denned : 



INVOLUCRE. The outer green circle of a flower-head, 

 often mistaken for a calyx. 



