11/18/2023
Here are six native oaks you can find in the eastern United States. If you’ve read Doug Tallamy’s “The Nature of Oaks,” you know that native oaks are the most important host trees for butterfly and moth caterpillars in North America. In addition, if you like to watch or listen to songbirds, native oaks provide the caterpillar food source for baby birds better than any other tree group.
As with other trees, additional features like the habitat, buds, acorns, and bark are often necessary for confident identification. Many oaks hybridize between species as well, sometimes making identification to species challenging from just the leaves.
Swamp White Oak (Quercus bicolor) can be found in bottomland forests and wetland margins across the Midwest and Northeast. There are some scattered populations in the Piedmont, though, and it’s also used in landscaping. The ‘bicolor’ in its scientific/botanical name refers to the difference between the dark green and glossy top surface of its leaves and the much lighter, silvery-white undersides.
Post Oak (Quercus stellata) grows in upland forests with clay soils in the Southeast. The leaves have a diagnostic Maltese cross shape and many star-shaped hairs (trichomes) on their lower surface.
Overcup Oak (Quercus lyrata) grows in bottomland forests of the Coastal Plain and in the Gulf Coast states. You’ll occasionally find one growing in the Piedmont, but they’re planted in landscaping too. Overcup Oak leaves are widest above the midline and typically have 7 lobes. The best feature to identify them may be their acorn, which has a cup that nearly encloses the entire nut.
Chinquapin Oak (Quercus muehlenbergii) can be found in the Midwest but it is sometimes planted in landscaping. In the wild, it’s often found around limestone outcrops. It has some resemblance to Chestnut Oak, but the leaves of Chinquapin Oak have sharper teeth along the margins. Chinquapin Oak leaves are also much smaller, typically being less than 5 inches long.
Chestnut Oak (Quercus montana) grows in upland forests of the Appalachian Mountains and adjacent Piedmont. The leaves can be up to 10 inches long and they have many rounded teeth along their margins. The key difference from Swamp Chestnut Oak leaves is that Chestnut Oak leaves are proportionately narrower.
Swamp Chestnut Oak (Quercus michauxii) grows in bottomland forests of the Coastal Plain and Gulf Coast states, but scattered populations occur in the Piedmont too. Its leaves are much wider above the midline and it has lots of rounded teeth along the leaf margin. The leaves closely resemble Chestnut Oak (Q. montana). The key difference between them, though, is that Swamp Chestnut Oak has proportionally wider leaves. It also differs in habitat and distribution range from the Chestnut Oak. Its scientific name honors the French naturalist André Michaux, who was the Royal botanist of King Louis XVI and an early explorer of the southeastern United States.
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