INDEX TO THE ARTIFICIAL KEYS 



Summer Keys : 



Key to the genera, xxi. 

 Key to the species of Acer, 172. 

 Key to the species of Aesculus, 194. 

 Key to the species of Betula, 84. 

 Key to the species of Carya, 66. 

 Key to the species of Catalpa,, 222. 

 Key to the species of Cornus, 202. 

 Key to the species of Fraxinus, 210. 

 Key to the 'species of Juglans, 60. 

 Key to the species of Picea, 18. 

 Key to the species of Pinus, 4. 

 Key to the species of Populus, 44. 

 Key to the species of Prunus, 152. 

 Key to the species of Pyrus, 142. 

 Key to the species of Quercus, 96. 

 Key to the species of Salix, 34. 

 Key to the species of Ulmus, 122. 



Winter Keys: 



Key to the genera, xxvii. 



Key to the species of Acer, 174. 



Key to the species of Aesculus, 195 



Key to the species of Betula, 85. 



Key to the species of Carya, 67. 



Key to the species of Catalpa, 223. 



Key to the species of Cornus, 203. 



Key to the species of Fraxinus, 211 



Key to itJhe species of Juglans, 61. 



Key to the species of Picea, 19. 



Key to the species of Pinus, 5. 



Key to the species of Populus, 45. 



Key to the species of Prunus, 153. 



Key to the species of Pyrus, 143. 



Key to the species of Quercus, 98. 



Key to tihe species of Salix, 34. 

 Key to the species of Ulmus, 123. 



aperies ui vJcui-x., ,54. 



species of Ulmus, 123. 

 241 



