Key to the Principal Tree Families 



DD. Bases of leaves unsym metrical. 



E. Fruit, a berry; leaves with three main 

 veins; bark warty. The Hackberries 



EE. Fruit dry with circular wing; leaves oval 



with prominent, straight veins. The Elms 

 EEE. Fruit a woody ball on leaf-like blade; 

 leaves large, distinctly one-sided. 



The Lindens, or Basswoods 

 CC. Leaves compound. 



D. Fruit, a flat pod. The Locusts 



DD. Fruit, a nut. 



E. Husk opening when ripe by four valves. 



The Hichories 

 EE. Husk not opening when ripe. The Walnuts 



i6 



