Area of a tree’s crotch where the growth of two limbs push into a ridge.

The branch collar is formed by the annual production of layers of tissue between the branch and trunk

Bark that becomes enclosed inside the crotch as two branches grow and develop.

Compartmentalization is the natural process by which a tree walls off the spread of decay.

Two tightly growing limbs (generally with no branch collar and having included bark) competing to be the leader.