ANTHOPHYTA. 



279 



the stigmas are ready for pollination, so that in these, 

 while the means for cross-pollination are perfect, self- 

 fertilization is rendered impossible. 



528. In the Oompositse (Fig. 167) the five anthers are 

 united into a ring or tube around the style. The pollen 



Fig. 167.— Flowers of Composites. A, of Dandelion, showing style pro- 

 truding through rings of anthers ; B, of Thoroughwort ; C, ditto, vertical 

 section showing style surrounded by anthers ; I), style showing two stig- 

 mas. All magnided. 



escapes from the inner side of the anthers into the anther- 

 tube, and at this time the immature style is short. As the 

 latter grows it pushes up through the anther-ring, carrying 

 the mass of pollen with it. Insects visiting the flowers for 

 nectar at this stage rub off the little piles of pollen from 

 the top of the stamen-tubes, and coming in contact after- 



