Quantum Leaf

The leaf is too wide to be E. tereticornis or E. propinqua, E.propinqua also has a strongly discolourous leaf and one of the typical characteristics of E. saligna (like any within the Mahogany Group) is the existance of leaf lerp, and generally profuse number of capsules.
Unfortunately without a capsule, bud or flower, identification is rarely certain. If it is a remnant species then you can narrow down the search, the suggestion of an intergrade (natural hybrid) is likely. It is common for some Eucs to skip a year or 2 from flowering. I generally find in the search for capsules and buds that if the area below the tree is maintained, then their is a chance of finding a capsule, bud stuck in a crotch, or close to the root flare where the mower dosn't reach. Otherwise the lack of these can also suggest that it is a very small capsule (like E.nicholii)that decays quickly, or is just difficult to find.
Their is an identification program called 'Euclid', which has an impresive key that can work without the bud or capsule.
Allowing for the number of species (approx. 850) as well as the intergrades, and variation within this genus, it would have to rate as one of the most difficult plant species in the world to identify.