ISA Certified Arborist Practice Exam

What does "branch collar" refer to?

1. The area at the base of a branch on a tree.

2. The area on a tree where a branch stems from the trunk.

3. The outer bark layer of a branch.

4. The part of the tree that connects roots to branches.

The correct answer is: The area on a tree where a branch stems from the trunk.

The term "branch collar" specifically refers to the area on a tree where a branch emerges from the trunk. This region is critical in tree biology and health because it's the part of the tree that contains the vascular tissue for both the branch and the trunk. The branch collar consists of specialized tissues that help in the healing process after a branch is pruned or breaks off, as it helps to protect the tree from decay and pathogens entering through the wound. This anatomical feature is important for proper pruning techniques, as cutting a branch too close to the trunk can damage the branch collar, inhibiting its ability to seal and heal effectively. Understanding this concept allows arborists to make informed decisions when caring for trees, ensuring they promote healthy growth and longevity.