42 A FIELD GUIDE IN NATURE-STUDY 



KEY TO TREES OF THE CHICAGO REGION BASED ON EASILY 



RECOGNIZED DISTINGUISHING FEATURES 

 A. Trees bearing cones and needle-like or scalelike leaves 

 that (except the larch) remain on the year round, i.e., 

 are evergreens 



a Leaves scalelike, overlapping Arbor Vitae or White Cedar 



aa Leaves needle-like 



b Needles 2-5 in clusters 



c Needles 5 in cluster White Pine 



cc Needles 2 in cluster, i-i| in. long Jack Pine 



(other pines occur in the parks) 

 bb Needles single 



c Needles spreading on opposite sides of twig 

 like barbs of a feather 



d Needles ^ in. or more long; bark blistery Balsam (Parks) 

 dd Needles less than | in.; bark not blistery Hemlock 



cc Needles sticking out all round twig 

 d Needles \ in. or so long 



e Needles in whorls of three, sharp- 

 pointed Common Juniper 

 ee Needles not whorled; not sharp- 

 pointed Spruce (Parks) 

 dd Needles less than \ in. long, sharp-pointed 



e A spreading shrub Creeping Juniper 



ee A pyramidal shrub or tree Red Cedar or Juniper 



AA. Trees not cone-bearing; leaves not needle-like but 

 broader, falling in autumn 

 a Leaves and twigs two or more at node 



b Most leaves (and leaf scars) three at node Catalpa 



bb Leaves (and twigs) two at node, opposite 

 c Leaves compound 



d Palmately compound; buds large, gummy Horse Chestnut 

 dd Pinnately compound 



e Twigs slender; leaf scars encircling 

 twig and meeting in a point 



Box Elder or Ash-leaved Maple 

 ee Twigs coarse; leaf scars not meeting 

 / Twigs square 



g In swamps; fruit wing tapering 



at both ends Water Ash 



gg In rich woods; fruit wing blunt 



both ends Blue Ash 



ff Twigs round 



g Branchlets downy Red Ash 



