KEY TO THE SPECIES OF ELMS 



1. Leaves doubly serrate, unequal at base. 



2. Some of twigs with corky wings ; fruit hairy, at least on margins ; 

 leaves not over 4 inches long. 



3. Buds and young twigs pale hairy; fruit appearing in spring, 

 ovoid to suborbicular, hairy and ciliate, seed cavity not 

 pronounced; leaves smooth above, hairy below; north from 

 Kansas, Missouri, and Tennessee to Quebec and Ontario 



U. thomasii, Rock Elm, p. 219. 



3. Buds and young twigs glabrous or nearly so; fruit oblong, 

 seed cavity pronounced; southern. 



4. Leaves 2-4" long, acuminate, glabrous above, slightly 

 hairy along veins below; fruit in fall, fringed on margin 

 with long white hairs; Kansas and Illinois to Georgia and 



Oklahoma U. serotina, September Elm, p. 217. 



4. Leaves l-2Vi " long; fruit covered with long white hairs. 



5. Leaves acuminate, coarsely doubly toothed, smooth 



above and hairy below; fruit in spring; Indiana and 



Virginia to Kansas and south 



U. data, Winged Elm, p. 217. 



5. Leaves rounded or acute at apex, unequally doubly 

 toothed, almost singly toothed; roughened above and 

 hairy below; fruit in fall; Arkansas to Mississippi and 



Texas U. crassifolia, Cedar Elm, p. 217. 



2. Twigs without corky ridges; fruit appearing in spring; seed 

 cavity distinct. 



6. Fruit hairy or ciliate; buds glabrous or with rusty hairs; 

 leaves usually 4—7 " long, rough on top. 



7. Buds with rusty hairs; fruit hairy over seed cavity; leaves 

 rough on both surfaces; bark of trunk dark red-brown; 



Quebec to North Dakota and south to Florida 



U. rubra, Slippery Elm, p. 219. 



7. Buds glabrous; fruit hairy only on margin; leaves rough 

 above; bark of trunk with alternating gray and brown 

 layers; Newfoundland to Saskatchewan and south to 

 Florida U. americana, American Elm, p. 217. 



6. Fruit glabrous; buds pale hairy or glabrous; European or- 

 namentals. 



8. Twigs hairv; leaves rough above; petioles Vq-IA " long. 

 9. Leaves 2-3" long; petioles 1/6-1/4" long; bark gray, 



furrowed ; seed near apex of fruit 



U. procera Salisb., English Elm 



9. Leaves 3-6 V2 " long; petioles Vq " long; barK dark, re- 

 maining smooth many years; seed near center of 



fruit U. glabra Huds., Wych Elm 



8. Twigs glabrous ; leaves 2-3 " long ; smooth above ; petioles 



V^-Vl" long. . U. carpinifolia Gled., Smooth-leaved Elm 



1. Leaves M-3" long, singly or nearly singly serrate, nearly equal at 



base, fruit glabrous; Asiatic ornamentals. 



10. Leaves H-2" long, predominately rounded to acute at apex; 



fruit in fall, ovate, notched at apex 



U. parvifolia Jacq., Chinese Elm 



10. Leaves 1-3" long, predominately acuminate to acute at apex; 



fruit in spring, suborbicular, with closed notch 



U. pumila L., Siberian Elm 



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