Leaf colors and Tree calluses

what: I believe it's an oak tree
where: on the way to St. Paul on Selby Ave. taken a few weeks ago when I was on a photo assignment
So- The plastid colors which are yellow, are where the tree has more shade. The parts of the tree that are exposed to more sunlight are where the red leaves appear because they are producing more anthocyanin.

What- Tree Callus
Where- Parking lot in back of house
This tree appears to have suffered a wound and could have been caused by people removing the branch. You can see the calluses and growth that occurred because of this wound.