510 



PLANT BREEDING 



Some of the most important results in variety making by 

 hybridization have recently been obtained in experiments on 

 the fruits of the rose family, particularly cherries, plums, and 



FIG. 370. Five forms of leaf from hybrid blackberries, all grown from the 

 seed of one plant and showing extraordinary variations in the amount of 

 incision in the margins of the leaflets, forming a regular series from a to e 



Modified after Burbank 



apples, and the citrous fruits. In the case of cotton and wheat 

 much effective work is also being done. 



The extraordinary successes of Luther Burbank in pro- 

 ducing new hybrid varieties of fruits and ornamental flowers 



o / 



FIG. 380 



a, a stoneless wild plum; 6, c, d, fruit of hybrids of a with the French prune. 

 All drawn to the same scale. Modified after Burbank 



have been widely discussed in the popular magazines. He has 



bred some remarkable hybrids, such as those between the 



j 



strawberry and raspberry, the apple and blackberry, the petunia 

 and the tobacco plant. These are of little use, though of much 

 scientific interest. Others of his hybrids, especially the plums, 

 are of great commercial value. Many other investigators, whose 



