Trees of New York State 61 



LEAF KEY TO THE SPECIES — (Continued) page 



141. Ijcaves 3-6 inches in diameter; margin coarsely dentate 



Populus grandidentata 131 

 141. Leaves 1^-3 inches in diameter; margin finely serrate. . Populus tremuloides 129 



142. Margin serrate or crenate 143 



142. Margin undulately or sinuately dentate 150 



143. Leaves narrowly ovate to ovate elliptical or oval; serrations fine 144 



143. Leaves oblong, lanceolate or obovate; serrations coarse 



Quercus Muhlenbergii 183 



144. Mature leaves pubescent beneath 145 



144. Mature leaves smooth or somewhat hairy on the veins beneath. , . . 146 



145. Leaves appressed pubescent beneath; leaf-margin obscurely crenulate 



Cornus alternifolia 317 

 145. Leaves white woolly-pubescent beneath; leaf margin irregularly serrate. . 



Pyrus Malus 235 



1 46. Margin incised-serrate Pyrus coronaria 233 



146. Margin not incised-serrate 147 



147. Petioles hairy 148 



147. Petioles glabrous 149 



148. Leaves 3-6 inches long, lustrous above, ciliate on the margin 



Populus candicans 137 



148. Leaves 4-8 inches long, dull above, not ciliate on the margin 



Populus heterophylla 133 

 149. Leaves ovate-lanceolate to ovate, 3-6 inches long, more or less rusty below. . 



Populus balsamifera 135 



149. Leaves ovate-oblong to oval, 2-4 inches long, not rusty below 



Pyrus communis 231 



150. Leaves white velvety-tomentose below Populus alba 127 



150. Leaves light green and quite smooth below Nyssa sylvatica 319 



151. Leaves pinnately compound 152 



151. Leaves bipinnately compound 171 



152. Leaves trifoliate Ptelea trifoliata 275 



152. Leaves 5 or more foliate 153 



153. Leaf-rachis winged Rhus copallina 283 



153. Leaf-rachis not winged 154 



154. Leaflets entire-margined 155 



154. Leaflets not entire-margined 157 



155. Leaves 1-3 feet long; leaflets 13-41 Ailanthus glandulosa 277 



155. Leaves 7-14 inches long, leaflets 7-19 156 



156. Leaflets obovate-oblong, coriaceous, acute at the apex, 3-4 inches 



long Rhus Vernix 285 



156. Leaflets ovate-oblong to elliptical, thin, mucronate or retuse at the 



apex, I5-2 inches long Robinia Pseudo-Acacia 273 



157. Leaflets 5-9 158 



157. Leaflets 9-41 162 



158. Three upper leaflets conspicuously larger than the others 159 



155. Three upper leaflets not conspicuously larger than the others 160 



159. Leaflets generally 5, glabrous or puberulous below Carya ovata 145 



159. Leaflets generally 7, soft pubescent below Carya laciniosa 147 



160. Leaflets glabrous or nearly so below; leaf-rachis smooth 161 



160. Leaflets pubescent below; leaf-rachis pubescent Carya alba 149 



161. Leaflets chiefly 5 or 7, oblong- or obovate-lanceolate Carya glabra 153 



Carya microcarpa 151 



161. Leaflets chiefly 9, lanceolate or oblong-lanceolate Carya cordiformie 155 



162. Leaflets even in number 163 



162. Leaflets odd in number 165 



163. Leaves 6-8 inches long, leaflets 1-2 inches long Gleditsia triacanthos 269 



163. Leaves 1-3 feet long; leaflets 2-5 inches long 164 



164. Leaflets sharply serrate except at the base, sessile or sub-sessile. . . . 



Juglans nigra 143 

 164. Leaflets entire except for a few coarse teeth toward the base, short 



stalked Ailanthus glandulosa 277 



165. Leaves 6-10 inches long 166 



