328 FRUITS AND SEEDS 



These are discussed in the section devoted to this topic 

 (see page 353). It must not be understood, however, that 

 dissemination, like pollination, is a process for which all 

 flowering plants must make definite provision. A vast 

 number of fruits and seeds have no regular means of dis- 

 semination. They simply drop to the ground beneath the 

 plant which bore them. Nuts, acorns, and many other 

 heavy fruits or seeds are examples of this. 



66. The Nature of Fruits. Fruits and seeds begin 

 where flowers leave off. They fulfill a work of reproduc- 

 tion to whose first stages the flowers are devoted. Fer- 

 tilization is followed by changes in the organs of the flower. 

 The most conspicuous of these changes is the growth of 

 the ovary. Its wall becomes the pericarp of the fruit. 

 The ovules develop into seeds. The corolla and the sta- 

 mens, their work having been accomplished, soon disap- 

 pear, but the calyx and the receptacle often enlarge with 

 the ovary. The structure which results from this growth 

 that follows fertilization is called the fruit. 



Young fruits are usually as green as the leaves. They 

 are able to manufacture much of the food used in their 

 own growth. In some trees, as in the elm, the green fruits 

 are prominent before the leaves appear, and in such cases 

 the work of photosynthesis which they do seems especially 

 important. 



A. Aid in Dispersal. Fruits aid in the dispersal of 

 seeds in three principal ways : 



a. By their Edibility. Many kinds of fruits are eaten 

 by animals through whose alimentary tracts the hard- 

 coated seeds pass without injury. This is not true, 



