ACKNOWLEDGMENT 



THE following companies and individuals have kindly 

 furnished the Author material for the illustrations referred 

 to by the figures opposite their names. 



Greening Nursery Co., Monroe, Mich.: 9, 13, 14, 25, 31, 38, 41, 

 60, 61, 62, 63, 66, 67, and 68. 



Stark Brothers Nurseries and Orchards Co., Louisiana, Mo.: 40 

 and 71. 



The Shenandoah Nurseries, Shenandoah, Iowa: 10, 19, 20, 21, 

 22, 23, 42, and 69. 



F. W. Watson & Co., Topeka, Kan.: 15, 16, 17, 18, and 70. 

 Department of Agriculture, Raleigh, N. C.: 33, 34, 35, and 36. 

 Extension Department, University of Maine: 54. 

 L. M. Dorsey, University of Maine: 6, 43, 45, 49, and 53. 



W. H. Volck, Watsonville, Calif.: 52. 



iv 



