The Trees of Vermont 129 



SUMMER KEY TO THE SPECIES OF ULMUS 



a. Leaves essentially smooth on both sides ; branches often with corky, 

 wing-like ridges ; lowermost branches usually short and strongly 

 drooping; main trunk usually continuous into the crown without 

 dividing, giving to the tree a narrow-oblong outline, 



U. racemosa, p. 135. 



aa. Leaves usually rough on one or on both sides ; branches without 



corky ridges ; lowermost branches not short, not strongly drooping ; 



main trunk usually dividing into several large limbs, giving to the 



tree a more or less vase-shaped outline. 



b'. Leaves usually rough above, but smooth beneath, with petioles 

 glabrous ; bark of trunk gray, deeply fissured into broad, scaly 

 ridges; inner bark not mucilaginous. . . .U. americana, p. 133. 

 Jyb. Leaves usually rough both sides, with petioles hairy ; bark of 

 trunk dark red-brown, shallowly fissured into large, loose plates ; 

 inner bark mucilaginous U. fulva, p. 131. 



WINTER KEY TO THE SPECIES OF ULMUS 



a. Buds conspicuously rusty-tomentose ; twigs more or less pubescent ; 

 inner bark very mucilaginous when chewed. . . .U. fulva, p. 131. 

 aa. Buds not conspicuously rusty-tomentose ; twigs glabrous ; inner 

 bark not mucilaginous. 



h. Bundle-scars usually 3 ; buds }i inch long, glabrous ; twigs with- 

 out corky ridges ; outline of tree vase-shaped, 



U. amerlcana, p. 133 



bb. Bundle-scars usually 4-6 in a curved line ; buds ^ inch long, 



somewhat pilose ; twigs often with corky ridges ; outline of tree 



narrow-oblong- U. racemosa, p. 135. 



