The Chestnut oak (Quercus montana, or Quercus prinus in some references) is one of the chestnut oak subgroup of the white oak group, genus Quercus section Quercus. It is native to the eastern United States, where it is one of the most important ridgetop trees from southern Maine southwest to central Mississippi, with an outlying northwestern population in southern Michigan. As a consequence of its dry habitat and ridgetop exposure, it is not usually a large tree, typically 20-30m tall; occasional specimens growing in better conditions can however become large, with trees up to 40-43 m tall known. The trees are usually not the best timber trees because they are usually branched low and not very straight, but when they grow in better conditions, they are valuable for timber. The timber is marketed as 'mixed white oak'.

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 Chestnut oak is easily distinguished from the Swamp white oak because that tree has whitened undersides on the leaves.

Extensive confusion with the Swamp chestnut oak has occurred, and some botanists have considered them to be the same species in the past. 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; however, this is not fully reliable.

The acorns of the Chestnut oak are 1.5-3 cm long and 1-2 cm broad, among 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.

The Chestnut Oak is commonly known by the name Quercus prinus, given by Linnaeus, but the original specimen included a mixture of leaves from this and other species, and Quercus prinus is now considered a confused name to be rejected. The next-oldest name Quercus montana, given by Willdenow, is now the name recommended for the species by the Flora of North America.

External links

• Flora of North America: Quercus montana (includes discussion of the scientific name)