334 



NATURE-STUDY 



band is rolled up and grown together at the lower end into 

 a little tube. In fact, the band may be considered a little 

 tubular corolla hke the morning-glory sHt open on one 

 side nearly to the base. In the sunflower and many other 

 such composites these outer strap-shaped, or ray, flowers, 

 as they are called, are merely for show, as they have neither 



pistil nor sta- 

 mens, and there- 

 fore do not form 

 seed. But in the 

 daisy, zinnia, and 

 many other flow- 

 ers they are not 

 sterile, but form 

 seeds. In the 

 central part of 

 the head are 

 other flowers 

 small and tubu- 

 lar, with both 

 stamens and pis- 

 tils which pro- 

 duce seeds. Note the two branched stigma projecting from 

 the centre of the httle flower. Tear the coroUa open and 

 note the circle of bro\^^l or yellow stamens surrounding the 

 style. The stamens open on the inside, and the style pushes 

 out the pollen as it grows out of the corolla; but it is not 

 self-fertihzed thereby because it is not yet ripe or ready for 

 pollination. 



The "flowers" of the sunflower, aster, daisy, and other 

 similar composita are thus seen to be composed of a large 



Fig. 133. Sunflower. 



(Not a single flower, but a head or cluster of many small flowers.) 



