140 THE SECOND BOOK OF BOTANY. 



head. The dandelion, thistle, aster, marigold, sun- 

 flower, daisy, dahlia, burdock, mayweed, bachelor's- 

 button, boneset or thoroughwort, golden-rod, lettuce, 

 saffron, cudweed or everlasting, wormwood, tansy, 

 yarrow, feverfew, camomile, ragweed, tickseed, ele- 

 campane, are familiar examples of such plants. For 

 your first observations select some flower-head in 

 which the parts are well developed, as the marigold, 

 thistle, or dandelion. Fig. 292 shows a thistle-head, 

 with lines pointing to its principal divisions. 



FIG. 293. 



Florets. 



Involucre of Bracta. 



Fig. 293 represents a marigold, in which the same 

 parts are shown. In Fig. 294 we look down upon 

 the top of the flower-head, and observe that it pre- 

 sents unlikeness of aspect, which is still more plainly 

 seen in the section (Fig. 295). 



