488 



STRUCTURE AND LIFE HISTORIES 



thus protected from becoming pollinated with the flower's 

 own pollen. As the styles emerge above the anthers their 

 two tips spread apart and roll back, exposing the infacing 



FIG. 373. A composite (Coreopsis sp.). A, B, E, views of the inflor- 

 escence or head; C, a ray-flower; D, section through the head; F } a disc- 

 flower in bud; G, disc-flower just opened; H, older disc-flower, the stigmas 

 reflexed; 7, disc-flower with corolla removed. 



stigmatic surfaces so that they may receive pollen brought 

 by insects from other flowers (Fig. 373). 1 



x The family Composite, as recognized above, including two series, 

 Tubuliflorae and Liguliflorse, is restricted by some authors so as to include 

 only plants having florets with tubular or both tubular and ligulate cor- 

 ollas in the head. Such plants as the chicory, dandelion, and lettuce, 

 having only ligulate corollas, comprise the family Cichoriaceae. Cichor- 

 iaceae and Compositae (hi this restricted sense) have syngenesious anthers. 

 Plants whose florets have tubular corollas only (sometimes none), but 

 anthers not truly syngenesious, comprise the Ambrosiasese, including the 

 rag- weeds, cockle-bur, marsh-elder (Iva), and Gcertneria. 



