DAISY, DANDELION, AND THISTLE FAMILY 



407 



fail of insect pollination, they frequently curl back, until they 

 touch the pollen collected on the style itself, and thus effect 

 self-pollination. These stages may be readily followed in the 



Fig. 137. Olearia insignis (I nat. size). 



dandelion. (c/. also Campanulaceae, p. 403). After pollina- 

 tion, the calyx tube usually grows upwards, bearing on its 

 summit a parachute of bristles or hairs (the pappus). In this 

 way the well known "clock" of the dandehon is formed. 

 The pappus hairs vary considerably in character, and generic 

 distinctions are sometimes based upon their differences. The 



