Reproduction in Multicellular Plants - 227 



Fig. 12-29. Diagram showing 

 the individual flowers of the 

 inflorescence of the sunflower. 



DISC FLOWER 

 RAY FLOWER 



only the "core" of the apple comes from the 

 ovule chamber. 



Fruits, like flowers, occur in almost end- 

 less variety; and frequently fruit structures 

 are important to the dispersal of the seeds — 

 by the wind, animals, or other agencies. This 

 relation may be seen in the following classi- 

 fication, which includes many of the most 

 common types of fruit. 



A. Dry Fruits 



1. Winged fruits or keys — as in maples, 

 elms, and ashes (Fig. 12-31). The wings, 

 which are outgrowths of the pericarp (wall of 

 the ovule chamber), foster seed dispersal by 

 wind. 



2. Plumed fruits, as in dandelions, syca- 

 mores, and milkweeds (Fig. 12-31). The 

 plumes are also pericarpal outgrowths that 

 facilitate wind dispersal. 



3. Barbed fruits, as in the burdock and 

 wild carrot. These fruits are dispersed as 

 "hitchhikers" on the fur or other skin cover- 

 ing of animals. 



4. Legumes, as in peas and beans. The 



capsule of this podlike type of fruit is de- 

 rived from a single ovule chamber. When 

 ripe, the pod splits open along both seam- 

 like margins, discharging the seeds. 



5. Grains, as in corn and wheat. Only the 

 very thin outer cover, which is closely ad- 

 herent to the true seed coat of these single- 

 seeded fruits, is derived from the pericarp 

 (Fig. 12-23). 



6. Nuts, such as hazel nuts and acorns. In 

 these single-seeded fruits, the thick, hard 

 outer shell is derived from the pericarp. 



B. Fleshy Fruits 



1. Berries, such as the grape and tomato 

 (Fig. 12-32). The "skin" and all the flesh of 

 the berry is derived from the wall of the 

 ovule chamber, which may be monocarpel- 

 late (grape) or polycarpellate (tomato) in 

 origin. Many berries are eaten by animals, 

 and a dispersal of the species may result 

 when the undigested seeds are voided in an- 

 other locality. 



2. Drupes, such as peaches and plums. Not 

 only the skin and flesh of these one-seeded 



