It manifests a strong tendency to hybridize with other oaks, and it readily crosses with black jack oak, pin oak, and yellow oak. It is believed that a cross between yellow oak and shingle oak produced the species known as lea oak. A mature tree may be one hundred feet high and three or four feet in diameter. It has a round or pyramidal attractive crown composed of many slender branches and twigs. The foliage is distinctively grouped at the ends of the twigs in star-like clusters. The leaves are four or six inches long, with wedge-shaped or rounded bases, and are deep green and shiny on the upper side, but lighter below. The acorns are short, stubby, and rounded, covered one-third of the way with thin shallow cups. Shingle oak grows rapidly, and it is often sold by nurseries which deal in ornamental forest trees. It is hardy as far north as Massachusetts. Although it bears great abundance of leaves, they are so arranged that the crown seems open. One may see through the branches of a large shingle oak, and it suggests an airiness not common with oaks. Differences of opinion exist concerning the value of shingle oak for commercial purposes. It belongs in the black oak group, and its wood goes to market as red oak, and apparently is never listed as anything else. It is never named in market reports; shops and factories never report it, and it has been pronounced inferior to red oak in strength and seasoning properties. Tests have been made of some of its physical properties, and the results do not indicate that the wood belongs with inferior timbers. Its breaking strength is given at 39 per cent greater than white oak, and its stiffness at 28 per cent greater. However, these values, which are calculated from Sargent’s tables, are based on tests of only a few specimens of the wood, and fuller investigation might make revision necessary. The wood is heavy, hard, and is said to check badly in drying. The pores are large and are arranged in rows; medullary rays are broad and conspicuous. The wood is light brown, tinged with red, the sapwood much lighter. The broad medullary rays, running radially, give the wood its good splitting qualities. The tree is fairly abundant in different parts of its range, and is cut and manufactured with other oaks and hardwoods. Slack coopers use it for barrels; box makers employ it for crates; chair mills saw dimension stock and ship it to factories to be finished; some goes to furniture factories; some is turned for spindles for grills, and for balusters for stairs; other fills various places as interior finish and molding. But it all goes to market and passes through factories under names other than its own.