﻿Trees of New York State 59 



LEAF KEY TO THE SPECIES — (Continued) page 



97. Leaves lanceolate-oblong, oval, or lance-obovate, thick textured 



Prunus serotina 245 



98. Leaf-petioles exuding a milky juice when broken 99 



98. Leaf-petioles not exuding a milky juice when broken 101 



99. Leaf-blades velvety tomentose below ; petioles usually 2-4 inches long 



Broussonetia papyrifera 211 

 99. Leaf-blades pale pubescent or nearly glabrous below; petioles less than 2 



inches long 100 



100. Leaves broadly ovate to ovate-orbicular, membranous, dull above, 



conspicuously reticulate-veined Morus rubra 21.3 



100. Leaves ovate to ovate-oval, firm, somewhat lustrous above, not con- 

 spicuously reticulate- veined Morus alba 215 



101. Leaf-blades inequilateral or oblique at the base 102 



101. Leaf-blades not inequilateral or oblique at the base 112 



102. Leaves ovate-lanceolate to broadly ovate, oval or orbicular; margin 



serrate 103 



102. Leaves ovate to ovate-oblong, elliptical or obovate; margin doubly 



serrate 106 



103. Leaf-blade conspicuously reticulate-veined; petioles less than one inch long. 



Celtis occidentalis 207 

 103. Leaf-blade not conspicuously reticulate-veined; petioles 1-3 inches long. . 104 

 104. Leaves smooth below aside from tufts of hairs in axils of prominent 



veins Tilia americana 307 



104. Leaves pubescent beneath 105 



105. Leaves grayish green beneath, densely pubescent TiHa. Michauxii 309 



105. Leaves grayish white pubescent beneath. .Tilia heterophylla, var. Michauxii 311 



106. Leaves thick; margin coarsely doubly serrate 107 



106. Leaves thin, margin finely doubly serrate 109 



107. Leaves exceedingly rough-papillose above Ulmus fulva 201 



107. Leaves smooth or nearly so above 108 



108. Leaves oval to obovate-oblong, dull and somewhat scabrous above. . . . 



Ulmus americana 203 

 108. Leaves oblong-oval to obovate, smooth and lustrous above 



Ulmus racemosa 205 



109. Leaves bright green above; base generally heart-shaped Betula lenta 161 



109. Leaves dull green above; base rounded or shallowly heart-shaped 110 



110. Petioles about J of an inch long Ostrya virginiana 157 



110. Petioles more than j of an inch long HI 



111. Petioles §-5 of an inch long Carpinus caroliniana 159 



111. Petioles j-1 inch long Betula lutea 163 



112. Petioles 1 inch or less in length 113 



112. Petioles more than 1 inch in length 139 



113. Leaf-margin coarsely indented; teeth acute or rounded 114 



113. Leaf-margin finely indented or at least with fine secondary teeth; teeth 



acute or rounded 118 



114. Leaf-margin coarsely serrate or dentate 115 



114. Leaf-margin coarsely sinuate or undulate-crenate 117 



115. Leaf-margin undulate-dentate; leaves lustrous above Nyssa sylvatica 319 



115. Leaf-margin coarsely serrate; leaves dull above 116 



116. Leaves membranous, smooth below; petioles about ^ inch in length. . . . 



Castanea dentata 173 

 116. Leaves thick, pale silvery pubescent below; petioles j-1 inch in length 



Quercus Muhlenbergii 183 



117. Leaf-margin undulate-crenate Quercus Prinus 185 



117. Leaf-margin sinuately-crenate Quercus macrocarpa 179 



118. Leaf-margin doubly serrate 119 



118. Leaf-margin serrate or crenate (sometimes obscurely doubly serrate in 



Primus virginiana) 126 



119. Leaves with 8 or more pairs of prominent secondary veins 120 



111). Leaves with 7 or less pairs of prominent secondary veins 125 



120. Petioles less than 5 of an inch in length 121 



120. Petioles 5 of an inch or more in length 122 



