When lightning strikes a tree, the high-voltage electricity flows through any water on the bark and through the sap under the bark.
This heats the sap to very high temperatures and instantly kills that part of the tree. Immediately after the strike it is common to see vertical black burn marks. Over time the tree tries to grow around the dead tissue and heal itself.
This leads to a vertical scar that runs from the ground to the highest parts of the tree. Lightning strikes on trees are more common in some species, like oak and ash, than others, like hawthorn. Typically the tallest trees on top of hills are hit most often.
In the photo above, the tree has tried to heal and ‘woundwood’ can be seen growing in from the edges of the dead area.
You will see lots of vertical scars on trees, but lightning scars are some of the few that run all the way from near the ground to the highest parts.
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