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
        • 31a – Leaf is triangular or diamond/wedge-shaped — go to 32
          • 32a – Petiole is round — go to 33

Current Step

• 33a – Female catkin appears as a woody “cone” persistent year-round.  Male catkin is papery and only present part of the year — Thinleaf Alder

• 33b – No woody, cone-like female catkin present.  Papery catkins may be present — Birch

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