Quercus engelmanii | Davis
This is a branch attachment of the mother of the preceding tree shown at Stanford. The mother is a lovely, upright, nicely-foliated tree, but exceedingly difficult to photograph in a meaningful manner. The swollen base connecting the branch to the trunk is often referred to as a branch bark ridge (BBR). Anatomical study has shown that the BBR is created by an overlap of trunk tissues and branch tissues. Cutting into the BBR is the same as cutting into the trunk, opening the trunk to long term decay. If only branch tissue is cut, and no trunk tissue, the chance of decay infection is greatly lessened. Thus, make the final cut on any limb removal into branch tissue only, just after the end of BBR, were the cross-sectional diameter becomes constant.