Archive for Sunday, November 27, 2011

Garden Calendar: Identifying winter trees is tough, but possible

November 27, 2011


Some trees, like the black walnut here, are easily identifiable by their bark.

Some trees, like the black walnut here, are easily identifiable by their bark.

While most people think about leaves when they think about identifying trees, there are many other unique characteristics that can help with identification. Winter is a good time to become familiar with trees’ other identifying features, including growth habit, bark, branch and leaf arrangement, twigs and buds. Proper identification may also require studying as much of the tree as possible.

A tree identification key will help only if it illustrates trees’ structural features or describes them in simple terms. Keys that are regional in nature also help to narrow down the choices. Two helpful dormant tree identification guides are “Trees, Shrubs, and Woody Vines in Kansas” (University Press of Kansas, $14.95) and “A Key to Missouri Trees in Winter” (Missouri Department of Conservation, $3).

Form and shape

The first thing to look for is the overall form. Some trees are distinctly recognizable from a distance. The most recognizable example is probably the American elm that typically grows into a distinct vase-like shape. Also, think of an oak tree with a broad, spreading crown and how it compares to a redbud’s short, sprawling nature. In most cases use tree form as just one factor in identification, as differences can occur from light competition, pruning and genetic variation.


Bark is the second feature to study in dormant tree identification. Again, characteristics are most distinct on mature trees as compared to young ones. Black walnut bark is one of the easier ones to identify, with its deeply furrowed gray-brown coloration. Chipping the bark surface (gently) reveals a chocolate-brown shade that makes me think of brownies with walnuts in them.

Birches are also recognizable by their bark, which peels back in thin sheets. Hackberry has a light gray, warty bark that becomes more furrowed as it ages. Sycamores and London planetrees have smooth, white or light-green patterned bark that stands out in the distance from the river bottoms and along Massachusetts Street in South Park. Shagbark hickory does just what its name implies.

Branch arrangement

Branch arrangement requires closer investigation of a tree. Branches originate in patterns described as alternate and opposite. Alternate branching habits are the most common. Alternate branching means that the branch origination occurs at alternating points on the branch — one branch here and the next one a few inches down on the other side. Opposite branching habit means branches occur directly across from each other on the branch.

Only a few tree species have opposite branching habits, so you can use this to quickly rule out many options. Maple, ash and dogwood are the most common (remember this with the acronym MAD). Buckeye and horsechestnut also have opposite branching but are uncommon in Kansas. Opposite branching is more common in shrubs, so make sure what you are identifying is a tree if it is an immature specimen.

Leaf arrangement

Leaf arrangement is similar to branch arrangement, but look closely for buds or bud scars to determine where the leaves originate. In addition to opposite and alternate leaf arrangements, leaves can emerge in a whorled pattern. Whorled leaf arrangement means multiple leaves emerge from the same point on the branch. Catalpa trees may have whorled or opposite leaf arrangements.

If the tree cannot be identified by form, bark and branch and leaf arrangement, the next step involves getting into the real nitty gritty of tree identification. Using a key, study leaf buds, leaf scars, stipules and lenticels — all of which have their own distinct characteristics in different tree species.

If the tree has fruit or seeds attached, they can also be used to aid in identification of the tree species.

Because evergreen trees can be identified by their leaves year round, dormant tree identification tips apply primarily to deciduous trees.

— Jennifer Smith is the Horticulture Extension Agent for K-State Research and Extension in Douglas County. She can be reached at 843-7058.


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