A branch collar is the "shoulder" between the branch and trunk of woody plants; the inflammation formed at the base of the branch is caused by annually overlapping trunk tissue.[1] The shape of the branch collar is due to two separate growth patterns, initially the branch grows basipetally, followed by seasonal trunk growth which envelops the branch.[1]
Branch collars serve as a strong foundation to the branch, and its orientation and internal characteristics allow the branch to withstand stress from numerous directions.[2] Functionally the branch collars also influence the conductivity of nutrients and growth patterns.[3][4]
The branch collar which provides a protective barrier to prevent infection and decay, can also be useful in diagnosing bacterial diseases.[1][5]
Proper pruning techniques should accommodate for the branch collar structure, as by damaging the tree it is likely to decay or become diseased.[1]
^ abcdShigo, Alex L. (1985). "How tree branches are attached to trunks". Canadian Journal of Botany. 63 (8): 1391–1401. doi:10.1139/b85-193.