THE COMPOSITE FAMILY 



67 



the upper part of it ends in five small and pointed teeth, indi- 

 cating its composition of five connate (gamopetalous) petals. 

 There a-re five stamens 

 inserted on the corolla 

 tube, their filaments are 

 separated, but their an- 

 thers are joined into a 

 tube (fig. 69, A.). The 

 anthers open on their in- 

 ner side (introrse) and set 

 the pollen free. The style 

 (Sty.), while seeking its 

 way through the very nar- 

 r w tube o f the an- 

 thers, cannot help pushing 

 up the pollen out of the 

 tube where the pollen ac- 

 cumulates in small clus- 

 ters (fig. 69, i). Insects 

 that visit the fiower are 

 sure to remove it with 

 their bodies and legs. And 

 then only the style opens 

 its two-forked stigma in 

 order to receive pollen 

 from another flower (fig. 

 69, 2). It is a well esta- 

 blished fact that fertiliza- 

 tion is generally achieved 

 not by the pollen of the 

 same fiower, but by that 

 of another. Self-fertiliza- 

 tion generally produces seeds of an inferior and degenerated sort. 

 We see in this case, as well as in many other plants, a wonderful 

 contrivance for cross-fertilization (compare Musssenda, page 63). 

 (6) Ligulate florets. — If insects have to render the flower this 

 very important service, they must also be attracted by some means. 



5* 



1 2 



Fig. 69. — Tubular florets of Sunflower (5 times 

 enlarged). The flower-tube is opened. Sc. Chaffy 

 scale of the receptacle. 0. Ovary. C. Calyx. 

 F. Filament. Sty. Style. A. Tube of joined 

 anthers (opened). St. Stigma. H. Spot where 

 honey is secreted. 



