Flora of North America species comparison

Quercus robur is one of the oaks most commonly cultivated in temperate and subtropical parts of the world. In North America it is most commonly seen in the eastern and northwestern parts of the United States and and in southeastern and southwestern Canada, where it tolerates a wide array of conditions and is extremely hardy. In Washington, New Brunswick, and Nova Scotia, apparently reproducing populations persist in the wild. Elsewhere, although actual naturalization appears to be rare, Q. robur should be expected to persist around old homesites and other places of cultivation.

Quercus robur most closely resembles our native species Q. alba in leaf form. In contrast with Q. alba, which has relatively long petioles (longer than 10 mm), acute leaf bases, and subsessile fruit (rarely on peduncles to 25 mm), Q. robur is easily distinguished by its shorter petioles (less than 10 mm), cordate, almost clasping, leaf bases, and fruit on long (more than 35 mm), thin peduncles.

Quercus robur is one of the oaks most widely celebrated in literature; it has wood of exceptionally high quality for the manufacture of furniture, and it previously was the most important wood used in the manufacture of wooden sailing vessels in Europe.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Varieties 2 (2 in the flora).

The question of the correct name for this species has persisted, with some authors rejecting the usage here in favor of Quercus durandii. Although no type material is extant, the original description of Q. sinuata is consistent with the concept presented here, as by W. W. Ashe (1916) and W. Trelease (1924), and inconsistent with any other oak from the broad area covered by Thomas Walter's Flora Caroliniana (1788).

The two varieties differ in habit, habitat, leaf size and lobing, and geographic range, and considerable variability exists within both varities as to the degree and density of silvery stellate-pubescence on the abaxial surface of the leaf. Sun leaves of both tend to have a higher proportion of silvery pubescence, and shade leaves and some individual trees tend to have more glabrate leaves, although evidence of flat-stellate trichomes is usually apparent. Plants with young, expanding leaves sometimes are mistaken for Quercus nigra, a member of the red oak group.

(Discussion copyrighted by Flora of North America; reprinted with permission.)