Chestnut oak
Scientific classification
Kingdom: Plantae
Division: Magnoliophyta
Class: Magnoliopsida
Order: Fagales
Family: Fagaceae
Genus: Quercus
Species: prinus
Binomial name
Quercus prinus
The chestnut oak (Quercus prinus, or Quercus montana in some references) is one of the chestnut oak subgroup of the white oak group, section Leucobalanus of the genus Quercus. It is one of the most important ridgetop trees in the eastern United States. The trees are usually not the best lumber trees because they are usually branched low and not very straight, but when they grow in better conditions, they are valuable for lumber. The timber is marketed as white oak.

The chestnut oak has the most massively-ridged bark of any eastern North American oak, and is readily identified by its dark gray bark. The leaves are virtually identical to those of the chinkapin oak, but the trees can readily be distinguished by the bark, because that of the chinkapin oak is a light ash-gray and somewhat peeling like that of the white oak. The chestnut oak is easily distinguished from the swamp white oak because that tree has whitened undersides on the leaves. However, it is difficult to distinguish from the swamp chestnut oak, and many botanists have considered them to be the same species. The chief way to distinguish the two is by habitat: if it grows on a ridge, it is chestnut oak, and if it grows in wet bottomlands, it is probably the more massive swamp chestnut oak.

The acorns of the chestnut oak are some of the largest of native American oaks, surpassed in size only by the bur oak and possibly swamp chestnut oak, and are a valuable wildlife food.

Although the epithet Quercus prinus was given by Linnaeus, the original specimen included a mixture of leaves from this and another species, so some botanists have used the substitute name Quercus montana.