There is a pretty general disposition to call this tree rock oak. The name refers to the hardness of the wood, and is not confined to this species. Other oaks are also given that name, and the adjective “rock” is applied to two or three species of elm which possess wood remarkable for its hardness. Cedar and pine are likewise in the class. In all of these classes “rock” is employed to denote hardness of wood. Iron as an adjective or ironwood as a noun is used in the same way for a number of trees. The name swampy chestnut oak as applied in some parts of the South to this tree, is hardly descriptive, for it is less a swamp tree than most of the oaks, though it does often grow along the banks of streams.
Its distribution ranges from the coast of southern Maine and the Blue Hills of eastern Massachusetts southward to Delaware and the District of Columbia; along the Appalachian mountains to northern Georgia and Alabama; westward to the shores of Lake Champlain and the valley of the Genesee river, New York; along the northern shores of Lake Erie and to central Kentucky and Tennessee. It is rare and local in New England and Ontario, but plentiful on the banks of the lower Hudson river and on the Appalachian mountains from southern New York to Alabama. It reaches its best development in the region from West Virginia to North Carolina, pretty high on the ridges flanking the mountain ranges.
Leaves are alternate, from five to nine inches long, with coarse teeth rounded at the top. At maturity, they are thick and firm, yellow-green and rather lustrous on the upper surface, paler and usually hairy beneath. In the autumn before falling, they turn a dull orange color or rusty-brown.
The flowers appear in May and are solitary or paired on short spurs. The fruit or acorn is solitary or in pairs, one or two and one-half inches long, very lustrous and of a bright chestnut-brown color. The acorn cup is thin, downy-lined and covered with small scales. The kernel is sweet and edible. The bark of the chestnut oak is thin, smooth, purplish-brown and often lustrous on young stems and small branches, becoming a thick, dark, reddish-brown, or nearly black on old trunks, and divided into broad rounded ridges, separating on the surface into small, closely appressed scales. The bark of the tree is so dark in color and so deeply furrowed that it has often been mistaken for one of the black oak group, although its wavy leaf margins and annual fruit clearly differentiate it from those species. The bark of the chestnut oak is thicker and rougher on old trunks than on any other oak.