Thursday, February 7, 2013

ID Trees of Winter

Honey locust or hawthorn?
Lately we have been trying to sharpen our winter tree identification skills.  Leaves not only provide us shade, they also are the main way we identify many trees and shrubs.  When the leaves leave, I have been left with the knowledge of some distinctive barks, and even that fails me in reliably separating a walnut and some hickories.

Shagbark hickory
Some trees are obvious.  Shagbark hickory has a bark easily identified by a child once they have seen it.  The sycamore can be identified at a distance by the distinctive white trunk where the bark peels away and by the seed balls hanging from the branches.  Not all trees are that distinctive, especially when young without their typical bark and fruit.

For many trees in winter, you have to identify them by their twigs and buds.  These distinctive features are present in all but the first months of leaf out and the spring growth spurt.  Identification is even more challenging when the unknown is small and could be a small tree or a shrub.  Like seeing a friend in a crowd, familiar features occasionally may pop out, letting you immediately identify a species you are familiar with.

Some young tree species have characteristics that are relatively distinctive.  Once you learn the face (twig or bud pattern) it can be yours forever (or for me as long as I can remember anything).  Features such as the presence of thorns, bark color and the shape of buds can put the plant in a group.  An example would be zig-zag twigs, which are easily identified and leads to a number of choices such as elm, sycamore, hackberry, redbud, osage orange and locust trees.  This MDC website lists twigs by a few of their distinctive characteristics.

A great place to learn some distinctive twigs and test yourself using pictures like those below is at  fieldbioinohio.blogspot.com/.   The picture of hawthorn thorns below on the left immediately made me think of honey locust but the twig wasn't right.  The hint to look for blood red buds in winter helps identify it as a hawthorn.  Lacking the buds, look for secondary spines off the main spine which will identify the tree on the right as a honeylocust.  I don't see red spines on our honeylocust at Bull Creek unless it is my blood.











This is an Ailanthus altissima or Tree of Heaven twig on the left.  These twigs are easily identifiable from a distance.  You can remember this by thinking of Little Red Ridinghood- "My what big leaf scars you have... the better to cut you down to your invasive stump."  The sassafras on the right has distinctive buds, especially when combined with the bright green twig, brown bark further down and the distinctive odor when it is broken or abraded.

For most twig identification I have to turn to a key.  That will be the subject of the next blog.

Special thanks to Field Biology of Southeastern Ohio for the use of the pictures.  It is a good place to test your eye.

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