Why Some Tree Branches Are Weaker Than They Look: Understanding Included Bark

What Is Included Bark?

When a branch develops from the trunk or another major branch, the connection between the two normally forms a strong structural union.

However, some branches grow at narrow angles. As the stems become larger, bark can become enclosed between them rather than being pushed outward naturally. This is known as included bark.

From a distance, the branch may appear completely normal. The tree may have plenty of leaves, healthy-looking bark, and no obvious signs of decay. The concern is the structure of the connection itself. A narrow union can create a point where the two stems do not have the same structural strength as a branch with a wider, more natural attachment.

Why Can Included Bark Be a Concern?

Trees constantly deal with forces from wind, rain, gravity, and the weight of their own branches. A strong branch union distributes these forces through the tree's structure, while a weak union may be less capable of handling those stresses, particularly as the stems become larger and heavier.

If two substantial stems are growing from the same point and one begins to fail, the damage can extend beyond the branch itself. A split can remove a large portion of the canopy, damage nearby property, or create a hazardous condition for people below.

This doesn't mean that every tree with a narrow branch union is automatically dangerous. Trees are complex organisms, and structural conditions need to be considered in context.

What Does Included Bark Look Like?

One of the easiest ways to notice a potentially weak branch union is to look at the shape where major branches meet. Instead of a broad, open angle, you may see two stems forming a tight V.

Other signs may include bark appearing trapped between two stems, a visible seam or ridge where branches meet, two similarly sized stems growing closely together, cracks developing around a branch union, a large branch extending from a narrow attachment, or previous damage or splitting around the connection.

Some of these signs can be difficult to identify from the ground, especially when the canopy is dense. That is one reason professional tree assessments can be useful for mature or structurally complicated trees.

Why Mature Trees Deserve Extra Attention

A small branch with a narrow connection may not seem particularly concerning when it is young. But trees grow. A branch that was once only a few inches in diameter can eventually become a major structural limb. As its size and weight increase, the forces acting on the attachment also change.

This is why structural issues are worth noticing early rather than waiting until a large branch has already failed. Regular observation can help property owners recognize changes before they become more difficult to manage.

Storms Can Put Weak Unions to the Test

Strong winds can place significant stress on a tree's canopy. Branches move, twist, and bend as the tree responds to changing weather conditions. A structurally weak connection may be more vulnerable when those forces become intense.

After severe weather, don't only look for branches that have already fallen. Look upward for newly visible cracks, split branch unions, hanging branches, broken limbs caught in the canopy, fresh wounds, branches that have shifted position, and sections of the tree that appear unstable.

A branch does not necessarily need to fall completely to become a concern. If something looks different after a storm, having the tree evaluated can help determine whether additional action is needed.

Can Included Bark Be Prevented?

Tree structure begins developing while the tree is young. Proper pruning during a tree's development can sometimes help encourage better branch structure and reduce the likelihood of certain structural problems becoming severe later.

However, mature trees cannot simply be reshaped without considering their existing structure. Removing a large branch incorrectly can create additional problems, including large wounds or unnecessary stress on the tree.

Tree pruning should therefore be based on the tree's species, age, structure, health, and growing environment rather than simply cutting away anything that looks inconvenient.

What About Trees With Multiple Trunks?

Multi-trunk trees aren't necessarily unhealthy or unsafe. Some trees naturally develop multiple stems, while others may produce competing leaders as they grow. The important question is not simply whether a tree has more than one trunk.

Instead, the structure of the connections matters. Two major stems growing from a strong, well-formed union are different from two large stems connected by a narrow union containing included bark. This distinction is one reason professional tree care involves evaluating the overall structure rather than relying on a single visual characteristic.

Why DIY Pruning Can Make Structural Problems Worse

When homeowners notice a branch that looks awkward, the natural reaction may be to cut it. But structural pruning isn't simply a matter of removing the biggest or most inconvenient branch. Cutting in the wrong location can leave a large wound, alter the tree's balance, or remove too much live canopy.

Even more importantly, homeowners may not be able to determine from the ground whether a branch is structurally weak or whether another part of the tree is contributing to the problem. For larger trees, branches near structures, or trees with visible cracks and major unions, professional evaluation is the safer approach.

When Should You Have a Tree Evaluated?

Consider scheduling a professional assessment if you notice a large branch forming a very narrow V-shaped union, bark trapped between two major stems, cracks near where large branches meet, a branch that has shifted after a storm, a large limb hanging over a house, driveway, or frequently used area, significant damage following severe weather, a mature tree with multiple large competing stems, or new changes in a tree's structure that you cannot explain.

A professional can look at the tree's overall condition and determine whether monitoring, pruning, or another form of tree care may be appropriate.

Healthy Leaves Don't Always Tell the Whole Story

One of the most important things to remember about tree care is that tree health and tree structure are not exactly the same thing. A tree can have green leaves and vigorous growth while still having a structural weakness. Likewise, a tree with an unusual shape isn't necessarily unhealthy or hazardous.

The goal isn't to remove every branch that looks different. The goal is to understand the tree's structure and identify conditions that may deserve attention.

Protecting the Trees Around Your Property

Trees provide shade, beauty, privacy, wildlife habitat, and character to a property. Keeping them healthy involves more than reacting after a branch falls. Paying attention to the way major branches develop can help property owners notice potential structural concerns earlier.

If you see a large tree with tightly attached stems, visible cracks, or other unusual branch unions, avoid climbing the tree or attempting major corrective pruning yourself. A professional tree service can evaluate the structure from a safer perspective and help determine the appropriate next step.

Final Thoughts

Included bark isn't always obvious, and it isn't automatically a sign that a tree must be removed. But it is a structural feature worth understanding. As trees grow larger, the shape and strength of their branch unions can become increasingly important. Recognizing narrow unions, trapped bark, cracks, and other structural changes can help homeowners know when a closer inspection may be worthwhile.

The best tree-care decisions begin with understanding what is happening inside the canopy—not simply reacting after a branch comes down. With regular observation and professional guidance when needed, property owners can take a more informed approach to caring for the mature trees around their homes and businesses.