A deciduous tree from 60 to 80 ft high, with a trunk 3 to 6 ft in diameter; young shoots warted, not downy; winter-buds brown, about 1⁄4 in. long, almost glabrous. Leaves oval or obovate, usually tapered, sometimes rounded at the base, with three to five lobes at each side, the lobes obliquely triangular or ovate, pointed, and with a few unequal teeth; the blade is 4 to 9 in. long, 4 to 6 in. broad, dark green and glabrous above, pale dull green or greyish beneath, usually with tufts of brownish hairs in the vein-axils; stalks yellowish, glabrous, 1 to 2 in. long. Acorns 3⁄4 to 11⁄4 in. long, nearly as wide, flat at the bottom, which is set in a shallow, almost saucer-shaped cup covered with closely appressed, short broad scales; they take two seasons to mature. Some trees (especially in the northern part of the area) bear fruits with narrower, more ovoid acorns and deeper cups.
Native of eastern N. America; introduced early in the 18th century. The red oak is undoubtedly the best grower among the American species introduced to Britain. In a young state it grows vigorously, and its fine, boldly cut foliage makes it one of the handsomest of deciduous trees. It frequently ripens acorns at Kew, from which young trees are raised. Its leaves change in autumn to a dull reddish or yellowish brown. The red oak is much confused with Q. coccinea and Q, palustris, but it has larger leaves than either, usually not so deeply lobed, dull beneath, and not so bright above.
The following are the most notable of the red oaks recorded in Britain in recent years. For comparison, it should be noted that the largest girth so far measured in the United States is 223⁄4 ft at 3 ft. Kew, Specimen Avenue, 70 × 103⁄4 ft (1963); N.E. of Pagoda, 65 × 103⁄4 ft (1963); near Japanese Gateway, 80 × 103⁄4 ft (1965); Oak collection, pl. 1874, 47 × 10 ft (1972); Cassiobury Park, Herts, 90 × 141⁄2 ft (1904), 100 × 193⁄4 ft (1965); Sindlesham, Berks, in Bear Wood, 80 × 163⁄4 ft (1970); Fairlawne, Kent, 72 × 143⁄4 ft (1965); Leonardslee, Sussex, 80 × 111⁄4 ft (1968); West Dean Arboretum, Sussex, 95 × 14 ft (1970) and 110 × 111⁄4 ft (1967); Pains Hill, Cobham, Surrey, 80 × 18 ft (1961); Westonbirt, Glos., in Main Drive, 90 × 11 ft (1967); Melbury Park, Dorset, 80 × 151⁄4 ft (1971) and 88 × 16 ft at 4 ft (1971); Patshull House, Staffs, 66 × 121⁄4 ft (1970); Killerton, Devon, 82 × 14 ft (1970); Gordon Castle, Moray, 85 × 11 ft (1956); Drumlanrig Castle, Dumfries, 85 × 131⁄4 ft (1970).
cv. ‘Aurea’. – In spring the leaves of this form of red oak are of a beautiful clear yellow, giving as bright an effect from a distance as flowers. To those who admire trees of this character it may be recommended as one of the best. It needs a sheltered spot with an evergreen background, and is nothing like so vigorous as the green-leaved type. According to Dr Boom, this oak arose in the Netherlands about 1878. There is an example at Kew measuring 50 × 53⁄4 ft and smaller ones in other collections. Award of Merit 1971.
Some botanists recognise var. borealis (Michx. f.) Farwell, with a more northern distribution, and differing not only in the deeper acorn-cup but also in the smoother, paler bark on the upper part of the trunk and the branches (Fernald, Gray’s Manual of Botany (1950), p. 546).
It has been suggested that the oak described by the younger Michaux as Q. ambigua is a hybrid between Q. rubra and Q. coccinea, and Elwes and Henry considered that some trees growing at Arley Castle, Worcs., were of this origin. The leaves were held late and coloured brilliant scarlet before falling, and the fruits resembled those described for Q. ambigua. Here it might be added that seed once distributed by the firm of Vilmorin under the name Q. ambigua had the reputation for producing trees that coloured well in the autumn. But Q. rubra is a variable species and Michaux’s Q. ambigua is now considered to be one of the many forms it assumes. Certainly there are no grounds for supposing that a tree of Q. rubra that gives good autumn colour is ipso facto a hybrid with Q. coccinea. Both species vary in that respect.