Bucida buceras, aka Black Olive Tree, Oxhorn Bucida or Shady Lady.
This Florida native is not the common edible olive, despite small, black seed-capsules. It's a tall evergreen tree with wind-resistant branches densely filled with lush, dark bluish-green, leathery leaves sometimes mixed with short spines.. The Shady Lady is also known in Mexico as a Bullet Tree.
Take care in planting location, as the black fruits emit a staining tannic acid.