30 KEY TO GENERA AND SPECIES 



brownish, forming scales with upturned pa- 

 pery margins Birch, 112. 



53. Leaves usually rounded at one or both ends. 



Bark without papery-margined scales Al- 

 der, 119. 



54. Blade nearly as wide as long, with an unsym- 



metrical and usually heart-shaped base 

 Linden, 198. 



54. Blade usually longer than wide, or with the 

 base nearly or quite symmetrical 55. 



54. Blade longer than wide and with an unsym- 



metrical base. Fruit very flat Elm, 144. 



55. Fruit fleshy or juicy, commonly globular, not 



splitting open at maturity. Wood com- 

 monly rather heavy and hard 56. 



55. Fruit neither globular, fleshy nor juicy; split- 

 ting open at maturity. Seeds with long 

 cottony hairs. Wood soft and light. Twigs 

 commonly brittle 58. 



55. Fruit small and dry, in large loose clusters, 

 splitting open at maturity. Seeds spindle- 

 shaped (long pointed at each end). Wood 

 heavy and hard. Leaves 4 or 5 inches long 

 and an inch or more wide, pointed at both 

 ends. Penn. southward and westward. 



