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Tree Bark Identification Key

 

Let me begin by saying that this is not intended to be a professional or all-inclusive key. It will not work for every species, but should enable you to identify the majority of trees in lower Midwestern latitudes when there are no leaves present. Identifying trees in the winter can sometimes be an art, but there are many characteristics you can look for to get a proper identification. This site is made as an attempt for the average person to be able to have a working chance at identifying trees in the winter. The key focuses on the best characters that one should use to identify the trees. It will work best for mature trees, as young trees have not developed many of their most distinguishing features.

The key is relevant for much of the Midwest, and down into the south a bit. The image below is the range for Shagbark Hickory, and most of the species on this page will have a similar range. The range probably goes from Illinois and Iowa, down into Missouri and Arkansas to the west. The range would continue eastward from those states and remain relevant for Indiana, Ohio, and Pennsylvania, down into West Virginia, Kentucky, and Tennessee. 

Range map for shagbark hickory.

These pages are still a work in progress, and will be updated continually. 

 

Tree Identification

The first thing to consider when working to identify a tree, iis whether or not the tree is a maple. This is the most common species, with over 50% of Indiana’s trees are some variety of maple. Maple probably has the most variation in bark of any tree species as well, so it can sometimes be quite difficult to determine by the bark alone.

Opposite Branching


First, look up at the branches of the tree. Are the branches opposite?

Do not look at the branches coming from the main trunk of the tree, but rather the smallest branches coming out of the tips. It is often helpful to look at them in contrast with the blue sky. If the branch tips are opposite, then you know you have a Maple, Ash, Dogwood, Buckeye, or a member of the Caprifoliaceae.

Ash tree alternate branching

Ash tree alternate branching

Remember the acronym MAD-Buck-Cap. It stands for MapleAshDogwood-Buckeye-Caprifoliaceae.

The group “Caprifoliaceae” consists of woody shrubs and flowering plants, so we will ignore it for our purposes.

If you are sure that your tree has opposite branching, then it will fall into one of these groups, so lets separate them out first.

Rule out Ash
Does your bark have a diamond or a “X” pattern with opposite branching? OR
Does your bark have an alligator skin” pattern with opposite branching?
Either of these or a combination of the two signifies an ash tree.

      U-Shaped Leaf Scar; Bud sits “in” scar
      White Ash

      D-Shaped Leaf Scar; Bud above leaf scar
      Green Ash

Rule out Dogwood
Is your Tree an understory tree? With a mature diameter less than 1 foot? AND
Is your bark “square-plated”?
If so, you have a dogwood.

Rule out Buckeye
Somewhat smooth bark, often has a splotchy look with a light gray color. Buckeye

Opposite Branching and none of the above? Then you have a Maple.
There are several different maple species within Indiana – the most common being sugar maple and red maple. Red maple can easily be separated out when there are leaves or buds on the branches, because the stems of the leaves or the buds will have red tones. For most purposes, just getting to maple will be enough, but here are some key characters of the different maples.

In a general sense:

Shaggy bark: Sugar Maple
Broad Ridges: Box Elder
Smooth Bark: Red Maple


Alternate Branching

All of the rest of the species will have alternate branching, but most have many other identifiable characters that can help with identification.

Is the bark smooth?

     Completely smooth bark. Leaves from previous year often still on tree, especially on younger trees in the understory.
     American Beech

     Trunk of tree has curves that look like muscles in a forearm.
     Blue Beech; Musclewood; Hornbeam; Ironwood – All different names for same tree.

     Paper-like bark with horizontal lines.
     Birch

               Bark peeling back in many places
               Yellow Birch or
                      Reddish or Pinkish tones to bark: River Birch

               Bark not significantly peeling back from trunk
               Paper Birch

     Big-Tooth Aspen

 


Lets get rid of some of the trees with other obvious features:

Is upper part of the tree white, where bark has apparently peeled off?
Sycamore

Standing back a little from the tree, is the bark gray with whiteish ovals carved out? (Look at pic)
Likely a Tulip Poplar. Often has an extraordinarily straight trunk.
Look up in the tree. There are commonly remnants of the seeds where the flowers were in the upper canopy.
Basswood can also look similar to Tulip Poplar.

Does the bark have individual nodules that noticeably extrude? (Look at pic)
Hackberry. Maybe a young sweetgum.

Is your bark blackish and broken up like individual cornflakes?
Then you have Black Cherry.

Are there long segments of thick, grey bark being shed going up the trunk?
Shagbark Hickory.

Does the tree have thorns on the trunk? Often 6” or more in length?
Honey Locust

Push on the bark, is slightly soft and spongy?
Probably looking at an elm. Often have “feet” or "buttresses" at base of tree. Crown often curved off to one side.
      Break off one of the bark segments.

      Is the interior of the segment alternating white and dark red?
      American Elm

      Is the interior of the bark alternating red/red segments?
      Red Elm (Slippery Elm)

Does your bark have an “X” pattern and is deeply furrowed?
I would start with thinking about Sassafras, Black Walnut, and Black Locust. If it is a very mature tree, then look into Tulip Poplar as well.

     Break off a small piece of the bark. Is it red-orange on the underside?
     Then you probably are looking at Sassafras. Confirm by smelling the bark, and it should have a distinctive, extremely fragrant smell. Sassafrass is usually a smaller tree that has a crooked trunk.

     Break off a small piece of the bark. Is it deep brown/black on the underside?
     Then you are probably looking at Black Walnut. Slice a branch down the middle. It should have a chambered pith.

     With deep furrows and no interesting color when the bark is broken.
     Then you are probably looking at Black Locust.

Does your bark have an “X” pattern and is not deeply furrowed?

     Opposite Branching.
     Ash

     Distinctive X pattern.
     Pignut Hickory

     Pattern appears almost melted into tree.
     Bitternut Hickory

Do the branches come out perpendicular to the trunk?
Stand at the base of the tree and look up. Do you see a pinwheel pattern?
Blackgum

Do twigs have corky projections? Spiny ball-shaped seed pods?
Sweetgum

Bark not deeply furrowed. Long longitudinal strips.
Basswood or Hop Hornbeam. Hop Hornbeam almost has a Sycamore style bark before it peels.

Standing back from the tree, do you see “ski-runs” going down the trunk?
Red Oak group

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