222 



Science of Plant Life 



described in recent publications devoted to plant production 

 and plant breeding. 



Variations. No two fruits, flowers, or other plant organs 

 are exactly alike. The variations may be small or large, and 

 there may be every gradation between the extremes of any 

 character. The several thousand sunflowers that might be 

 grown from a pound of seed would vary in height of stem, 

 amount of branching, and size of flowers. Not only may 

 there be variations in the structures of plants, but there may 

 also be variations in the composition of the plant organs. 

 For example, the great variety of colors, flavors, and other 

 qualities in apples is due to variations in the composition of 

 this fruit. The variation in each of these characters is quite 

 independent of variations in the others. It is possible, there- 

 fore, to get all kinds of 

 combinations of different 

 characters, and by careful 

 breeding and selection to 

 combine many desirable 

 qualities in a single plant. 

 The Shasta daisy, for ex- 

 ample, was made by breed- 

 ing together the English, 

 American, and Japanese 

 daisies, and combining in 

 one plant the pleasing foli- 

 age of the English species, 



FIG. 138. Two plants of sweet corn of the the free-blooming habit of 

 same variety, one grown in poor soil and the American daisy, and the 



waxy luster of the petals of 



one in soil to which fertilizer was added. 

 The differences in the plants are due to the 

 environment. 



the Japanese plant. 



