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1 Most of the leaves on a relatively mature tree entire and unlobed (some species frequently with some leaves on a tree, especially those on young or vigorous growth, that are toothed or shallowly lobed, the teeth or lobes generally few and irregular in size or location); [primarily either “laurel oaks” of section Lobatae or “live oaks” of section Virentes]
1 Most of the leaves on a relatively mature tree lobed or toothed.
..2 Venation of the leaves neatly and evenly pinnate, the 3-17 (or more) main lateral veins on each side distinctly parallel to each other, each ending in a tooth or shallow, crenate lobe extending < ¼ of the way to the midrib; [“chestnut oaks” of sections Quercus, Cerris, and Cyclobalanopsis]
..2 Venation of the leaves pinnate, but more branched and irregular, the 1-7 main lateral veins on each side rebranching into prominent side veins, the leaf usually distinctly lobed, at least some of the lobes of some of the leaves of a tree extending > ¼ of the way to the midrib.
....3 Apices of the lobes or teeth obtuse (rarely acute), lacking bristle tips; scales of the acorn cup thickened and tuberculate, not obviously imbricate; [“white oaks” of section Quercus]
....3 Apices of the lobes or teeth acuminate (rarely acute), and with bristle tips; scales of the acorn cup flat and imbricate; [“red oaks” of section Lobatae]