62 THE PLANT: A GENERAL EXTERNAL VIEW 



helps maintain the life of the race. Roots, stems, and 

 leaves are organs of nutrition ; the flower is an organ of repro- 

 duction. Leaves are 

 principally for photo- 

 synthesis. Flowers 

 are exclusively for seed 

 production. The way 

 in which they produce 

 seed is described in a 

 later chapter. 



20. Fruits. At the 



grocer's we buy fruits 

 and vegetables. The 

 grocer has no difficulty 

 in telling a fruit from 

 a vegetable, but he 

 would have great dif- 

 ficulty in telling what 



FIG. 13. "Brown-eyed Susan" (Rudbeckia). f^ftg an( J vegetables 

 The part commonly called the " flower " of this 



plant is composed of many small flowers such are. 1 ry it yOUrsell to 



as are shown, in three stages, at the left. ggg These tWO terms 



are convenient, but not exact. An exact term stands for 

 a definite idea, and only exact terms can be accurately 

 defined. You can make lists of fruits and vegetables, 

 but a list is not a definition. 



Exact terms may not be necessary in the grocery busi- 

 ness, but they are very necessary in science. So in science 

 the word fruit is used to denote that structure, whatever its 

 appearance, which follows the flower and contains the seeds. 

 Thus a tomato, though a vegetable to a grocer, is a fruit 

 to a botanist. 



