Previous Steps

• 1b – Alternate leaf arrangement on stem — go to 18
  • 18a – Leaf simple — go to 19
    • 19b – Thornless — go to 22
      • 22e – All leaves unlobed — go to 31
        • 31d – Leaf is oval or oblong (twice as long as wide) — go to 40
          • 40b – Leaf base symmetrical — go to 43
            • 43b – Leaf margin not wavy or only slightly wavy; margin obviously toothed — go to 44
              • 44b – Petiole less than 1 inch long — go to 45
                • 45a – Very strong pinnate venation; mostly straight veins extending almost to the margin; usually unforked — go to 46
                  • 46b – Margins coarsely toothed, doubly toothed, or almost lobed. Buds long and pointed — go to 47

Current Step

• 47a – Pith round. Papery catkins may be present; female catkins do not appear as woody “cones” — Birch

• 47b – Papery male catkins may be present; female catkins appear as woody “cones” and are present — Thinleaf Alder

Resources

• Identifying Broadleaf Flowering Trees and Shrubs, CMG GardenNotes #173
• List of trees in this key
• Glossary of Terms
• Front Range Tree Recommendation List
• Online CSU Extension publications on Tree and Shrub Selection