| ID Characteristic | The chestnut oak is readily identified by its massively-ridged dark gray-brown bark, the thickest of any eastern North American oak. The leaves are 12-20 cm long and 6-10 cm broad, shallowly lobed with 10-15 rounded lobes on each margin; they are virtually identical to the leaves of swamp chestnut oak and chinkapin oak, but the trees can readily be distinguished by the bark, that of the chinkapin oak being a light ash-gray and somewhat peeling like that of the white oak and that of swamp chestnut oak being paler ash-gray and scaly. The chinkapin oak also has much smaller acorns than the chestnut oak. The chestnut oak is easily distinguished from the swamp white oak because that tree has whitened undersides on the leaves. |
| Bark/Stem Description | Dark, fissured into broad ridges, scaly. Branchlets stout, at first bronze green, later they become reddish brown, finally dark gray or brown. Heavily charged with tannic acid. |
| Flower/Leaf Bud Description | Light chestnut brown, ovate, acute, one-fourth to one-half of an inch long. |
| Leaf Description | Alternate, 12-20 cm long and 6-10 cm broad, obovate to oblong-lanceolate, wedge-shaped or rounded at base, coarsely crenately toothed, teeth rounded or acute, apex rounded or acute. They come out of the bud convolute, yellow green or bronze, shining |
| Flower Description | Staminate flowers are borne in hairy aments two to three inches long; calyx pale yellow, hairy, deeply seven to nine-lobed; stamens seven to nine; anthers bright yellow. Pistillate flowers on short spikes; peduncles green, stout, hairy; involucral sc |
| Fruit Description | The acorns are 1.5-3 cm long and 1-2 cm broad, among the largest of native American oaks. Annual, singly or in pairs; nut oval, rounded or acute at apex, bright chestnut brown, shining, one and a quarter to one and one-half inches in length; cup, cup |