Fagaceae, the Beech Family
Trees (or 1 species shrubby), with alternate simple leaves and monoecious flowers, the staminate flowers in catkins, and the pistillate solitary or in small clusters. Fruit a nut (or acorn) enclosed in a cup or bur.
| 1a. Leaves serrate with numerous sharp-pointed teeth — 2. | |
| 1b. Leaves serrate, lobed, or entire, but never serrate with sharp-pointed teeth; fruit an acorn; pith 5-angled in the young twigs (Oak) — 3. | |
| 2a. Bark gray, smooth; buds 3-4 times longer than wide; nut | Beech, Fagus grandifolia. |
| 2b. Bark rough; buds relatively thicker; nut rounded | Chestnut, Castanea dentata. |
| 3a. Leaves entire, except for a bristle at the tip | Shingle Oak, Quercus imbricaria. |
| 3b. Leaves toothed or lobed, the points bristle-tipped — 4. | |
| 3c. Leaves toothed or lobed, the points without bristles — 10. | |
| 4a. Leaves entire below the middle, with a few shallow lobes beyond | Black Jack Oak, Quercus marilandica. |
| 4b. Leaves deeply lobed throughout — 5. | |
| 5a. Cup of the acorn saucer-shape, covering less than one-third of the acorn — 6. | |
| 5b. Cup of the acorn hemispherical or top-shape, covering one-third or more of the acorn — 8. | |
| 6a. Length of the lateral leaf-lobes less than one-third the width of the leaf; acorn cup 2-2.5 cm. wide | Red Oak, Quercus rubra. |
| 6b. Length of the lateral leaf-lobes more than one-third the width of the leaf — 7. | |
| 7a. Acorn depressed-globose, about 1 cm. in diameter | Pin Oak, Quercus palustris. |
| 7b. Acorn ovoid, 1.5-2 cm. thick | Schneck’s Oak, Quercus schneckii. |
| 8a. Leaves pubescent beneath | Black Oak, Quercus velutina. |
| 8b. Leaves glabrous beneath — 9. | |
| 9a. Buds glabrous; inner bark of the trunk yellow | Hill’s Oak, Quercus ellipsoidalis. |
| 9b. Buds pubescent beyond the middle; inner bark of trunk red | Scarlet Oak, Quercus coccinea. |
| 10a. Leaves deeply pinnately lobed — 11. | |
| 10b. Leaves crenate, dentate, or sinuate, not lobed — 12. | |
| 11a. Leaf divided nearly to the middle by a pair of deep lateral lobes near the middle of the leaf; acorn more than half covered by the cup | Bur Oak, Quercus macrocarpa. |
| 11b. Leaf without a median pair of deeper lobes; acorn about one-fourth covered by the cup | White Oak, Quercus alba. |
| 12a. Leaves broadest at or near the middle, with numerous (8-13) sharp coarse teeth on each side | Yellow Oak, Quercus muhlenbergii. |
| 12b. Leaves broadest above the middle, with a few shallow, rounded or subacute teeth (7 or less on each side) — 13. | |
| 13a. Large tree; leaves densely white-tomentose beneath; acorn on a stalk 3-10 cm. long | Swamp White Oak, Quercus bicolor. |
| 13b. Shrub; leaves thinly white-tomentose beneath; acorn sessile or nearly so | Scrub Oak, Quercus prinoides. |