Monday, February 2, 2015

Winter Identification of Deciduous Trees by Audrey Stokes

For most of us, tree identification begins with leaves. Typically, it is the only characteristic of the tree that we ‘dabbling foresters’ examine. Identification of deciduous trees in the winter can be more of a challenge but not impossible when other characteristics are considered.

To make matters easier keep in mind that in one forest location in Colorado you will generally find only five or ten types of trees. There are only some fifty kinds of trees native to all of Colorado, or even less if you do not count those which often grow as large shrubs - low diversity for such a large forested region, some 25,000 square miles, with many habitats.

If you are attempting to identify native trees you can take several things into account.
  • Elevation: Plains Cottonwood (Populus deltoides) does not grow at elevations above 6500’ but Narrowleaf Cottonwood (Populus augutifolia) can be found growing at 8000’ elevations.
  • Habitat: Gambel’s Oak (Quercus gambelii) often called scrub oak, grows as shrubs as low as 4 to 6 feet high in dry locations but Boxelder (Acer negundo) usually grows along streams.
  • Twig markings: The bundle and leaf scars offer information as to how leaves are arranged when present. They can also tell you where the buds grow. Virginia Tech has a great twig key ( that will take you step-by-step in determining what tree your twig came from.
  • Branching pattern: Ash (Fraxinus species) trees have an opposite branching pattern where side branches and leaf scars are directly across from each other on the stem. Elm (Ulmus species) trees have an alternate branching pattern where side branches are not directly across from each other.
  • Bark: All specie’s bark has a difference in color, thickness, texture and pattern. Learning the feel of the bark with your hands will help you remember the bark more quickly than remembering its visual pattern. Feel for hardness and scaliness as well. Quaking Aspen (Populus tremuloides) has green-white, smooth and thin bark with raised dark patches. Hackberry (Celcis occidentalis) is noted for its warty bark.

Cottonwood (Populus deltoids) bark is deeply furrowed at maturity. 

Hackberry (Celcis occidentalis) is noted for its warty bark.

Scrub oak (Quercus gambelii) bark is light gray, thick, ridged or deeply fissured, or in irregular plates or scales. 
Go out there and put your winter tree identification skills to the test…but before setting out in the cold, make sure to bring along a good field guide to assist you in figuring out what is what!

Pictures of tree bark:
Pictures of tree branches:
Key to Identifying Common Colorado Landscape Trees:
Tree Identification Field Guide by Arbor Day Foundation:
Colorado's Major Tree Species: