Illustrated key of oaks

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NOTE: This key is primarily based on leaf characters. The typical "sun leaf" characters used in the key may not be as apparent in "shade leaves", therefore it is best to look at leaves in several parts of the tree. Leaves on immature trees also may not be typical for the species and it may not be possible to reliably identify those individuals.

1. Leaves unlobed and entire: go to 2

1. Leaves lobed or coarsely toothed: go to 3

2. Leaves relatively wide (>2.5 cm), lower surface hairy:
Quercus imbricaria (shingle oak)

2. Leaves relatively narrow (<2.5 cm), lower surface not hairy or hairy along the midvein:
Quercus phellos (willow oak)

3. Leaves coarsely toothed, without deep sinuses and lobes: go to 4

3. Leaves distinctly lobed, with deep sinuses (grooves) between lobes: go to 7

Note: Characters of this group may overlap. Examine all available features to decide among these four species.
4. Trees of dry slopes or mesic woods, lower surface of leaf may be hairy but not velvety to the touch : go to 5

4. Trees of wetlands, lower surface of leaf velvety to the touch between the veins : go to 6

5. Coarse teeth rounded, acorn > 2.5 cm long bark deeply furrowed,:
Quercus montana (chestnut oak)

5. Coarse teeth gland tipped, acorn < 2.5 cm long, bark thin and flaky:
Quercus muehlenbergii (chinkapin oak)

6. Leaf with fewer than 9 pairs of main veins, some veins not ending in lobes, lobes may be gland tipped, acorn with a long stem 2-7 cm long, bark dark, thick and furrowed:
Quercus bicolor (swamp white oak)

6. Leaf with 9 or more pairs of main veins, most veins ending in lobes, acorn with a short stem, bark light gray, thin and flaky:
Quercus michauxii (swamp chestnut oak)

7. Lobes of leaves with rounded ends, not bristle-tipped: go to 8

7. Lobes of leaves pointed and bristle-tipped: go to 11

8. Leaf lobes forming a cross shape, leaves leathery with surface covered with stellate (arranged in a star) hairs (use hand lens):
Quercus stellata (post oak)

8. Leaf lobes not forming a cross shape, leaves not leathery and without stellate hairs on surface: go to 9

9. Leaf lobes and sinuses fairly uniform in length and size, acorn less than half covered by a pebbly cap, bark thin and tending to form irregular flakes:
Quercus alba (white oak)

9. Leaf lobes varying in size with sinuses sometimes deep near the base of the leaf, acorn more than half covered by the cap, bark ridged or with more regular flakes: go to 10

10. Leaf tending to have larger lobes near the tip, large acorn with distinctively fringed cap:
Quercus macrocarpa (bur oak)

10. Leaf somewhat lyrate (similar to the shape of a dandelion leaf), small acorn sometimes nearly completely covered by cap and without a distinctive fringe, wetland tree:
Quercus lyrata (overcup oak)

11. Leaves broadly 3-lobed at apex, narrowing at base, bark dark and blocky, tree of dry ridges:
Quercus marilandica (blackjack oak)

11. Leaves distinctly pinnately lobed on at least some of the leaves: go to 12

12. Leaf terminal lobe bent to one side (falcate), base of leaf bell shaped:
Quercus falcata (southern red oak)

12. Leaf terminal lobe not bent to one side, base of leaf angled rather than rounded: go to 13

13. Leaf lobes relatively wide with sinuses between lobes indenting less than half way to midrib, bark of mature trees with characteristically broad flat-topped vertical ridges, buds small, reddish, and sparsely hairy:
Quercus rubra (northern red oak)

13. Leaf lobes relatively narrow with sinuses between lobes indenting more that half way to midrib, bark of mature trees may be ridged, but without characteristically broad tops (Q. coccinea may have somewhat flattened ridges), buds may or may not be hairy: go to 14

14. Terminal buds large and covered entirely with thick blond hair (velutinous), lower leaf surface with yellowish pubescence which may cover the entire surface or be primarily in the vein axils:
Quercus velutina (black oak)

14. Terminal buds without blond hair or hairy only on the upper half, lower leaf surface without yellowish pubescence: go to 15

15. Terminal buds hairy on upper half, acorns with concentric rings at tip, leaves may be bright red in fall, tree of dry uplands:
Quercus coccinea (scarlet oak)

15. Terminal buds not hairy, acorns without rings at tip, leaves not red in fall, trees of lowlands or mesic forests: go to 16

16. Leaf lobes narrowing at tips, twigs without a waxy gray covering, branches sticking straight out like the spokes of a wheel, tree of wetlands but often planted as a street tree:
Quercus palustris (pin oak)

16. Leaf lobes widening at tips, sometimes forming circular sinuses, twigs (and to some extent acorns) may have be covered with a waxy gray covering, branches ascending, a tree of mesic forests:
Quercus shumardii (Shumard's oak)