Thanks to treedictionary.com
Codominant stems and Included bark
Codominant (two equally dominant) stems are stems that originate at about the same position on the trunk and grow about the same diameter. The problem is that over time the stems may push against each other and cracks may form at the bottom of the vee formed by the two stems. If cracks do form, the stems become a high risk for failure at low or moderate loading.
This was a problem with the 'Bradford' Callery pears and why they were apt to loose branches for no apparent reason.
Included bark
The dissection to the left are codominant leaders. Notice the included bark down the middle (White arrow). A point worth mentioning is the the included bark formed when the tree was younger. When the bark was formed it was on the outside of the stems and not included. As the stems increased in diameter, the vee between the braches closed at the base.
Included Bark and the Branch Bark Ridge
The yellow pencil on the right points to the raised branch bark ridge (BBR). This is a good union at this time. The blue pencil on the left points to the spot where the branch bark ridge turns inward and included bark developed.
