212 



PRACTICAL COURSE IN BOTANY 



you see the ovule? Where is it attached? (Use a mature 

 akene for this purpose.) In most plants of this family, the 

 akene is surmounted by delicate hairy bristles, as in the 

 dandelion, wild lettuce, and groundsel ; or by small chaffy 

 scales, as in the sneezeweed and sunflower, and sometimes 

 by hooks and barbed hairs, like those of the tickseed, bur 

 marigold, and cocklebur. These appendages constitute the 

 pappus. They are modifications 

 of the sepals, and serve an impor- 

 tant purpose in aiding the dis- 

 tribution of the seed. Can you 



309 



310 



312 



313 



314 



FIGS. 309-314. Akenes of the composite family : 309, mayweed (no 

 pappus); 310, chicory (pappus a shallow cup); 311, sunflower (pappus of two 

 deciduous scales); 312, sneezeweed (Helenium, pappus of five scales); 313, sow 

 thistle (pappus of delicate downy hairs) ; 314, dandelion, tapering below the 

 pappus into a long beak. (After GRAY.) 



suggest some of the ways in which they may aid in accom- 

 plishing this object? 



235. The stamens and pistil. Remove the corolla of a 

 disk flower carefully so as not to disturb the inclosed organs, 

 and notice how the stamens are united into a tube by their 

 anthers. Flatten out the tube and make an enlarged sketch 

 of it, showing the long, narrow shape of the anthers and their 

 mode of attachment. Can you make out how they open to 

 discharge their pollen? Examine one of the younger florets 

 near the center of the disk, and observe that the tip of the 

 style is inclosed in the anther tube with the lobes of the 

 stigma pressed tightly together by their inner faces (Fig. 315), 

 so that it is impossible for any of the pollen to reach the stig- 



