COMPOSITE. 



279 



441. The pappus and syngenecious stamens.— The calyx 

 tube in the aster, as in all of the composites, is united with the 



ovary, while the limb is free. 

 In the aster, as in many 

 others, the limb is divided 

 into slender bristles, the pap- 

 pus. (In some of the com- 

 posites the pappus is in the 

 form of scales. ) The stamens 

 are united by their anthers 

 into a tube (syngenecious) 

 which closely surrounds the 

 style. (In ambrosia the an- 

 thers are sometimes distinct.) 

 The style in pushing through 

 brushes out some of the 

 pollen from the anthers and 

 bears it aloft as in the bell- 

 flower, but the stigmatic sur- 

 face is not yet mature and 



Aster novze-angliae. 



Fig. 239. 

 Head of flowers of Aster novse-anglia 



expanded, so that close pollination cannot take place. There 

 are usually no stamens in the ray-flowers. The ovary is com- 

 posed of two carpels, as i.s shown by the two styles, but there 

 is only one locule, containing an erect, anatropous, ovule. 



