Northern Ontario Plant Database
Quercus rubra L.
En: northern red oak, red oak
Fagaceae (Beech Family)
General: A tall deciduous tree, 20—30 m tall; northern red oaks are fast-growing when young, moderately shade tolerant, have a deep, wide-spreading root system, and are often planted as a landscape tree in urban areas due to their tolerance to air pollution. The dense hard wood of northern red oak is used for lumber and making furniture, flooring, and railroad ties.
Stems/twigs: Twigs are smooth (glabrous), slightly 5-angled, and grayish-brown to reddish-brown; the terminal bud, 4—7 mm long, and a few slightly smaller lateral buds are clustered at the broader tip of the twig. Both terminal and lateral buds are ellipsoid to conical, pointed (acute), and have 4—5 rows of overlapping (imbricate) ovate bud scales aligned in 5 vertical columns. Bud scales are dark reddish-brown and glabrous, except for a fine fringe of short hairs along the margins of upper bud scales. The pith is 5-angled to star-shaped in young twigs. The furrowed bark is dark grayish brown to nearly black on some younger trees, with flat ridges and shallow, slightly paler furrows.
Leaves: Alternate, simple, and pinnately-lobed, with a slender petiole 2.5—5 cm long. Leaves have 7—11 bristle-tipped lobes, which are indented about ¼—½ the distance to the midrib. Leaf blades are oblong to ovate in general outline, 12—20 cm long by 6—12 cm wide, dark green and shiny to dull above, paler and dull beneath, hairy when young with pinkish pubescence, but becoming smooth (glabrate) above. Leaf bases are narrow to broadly tapering (cuneate); each lobe tapers at the tip to a very slender bristle. Margins are entire and rounded between lobes; near the tip of the lobes are 1—3 coarse teeth, each of which terminates in a long bristle. Leaves of trees grown in the shade are often very shallowly lobed with shorter bristles, compared to leaves of trees grown in the open sunny locations.
Flowers: Unisexual, very small, with separate male and female flowers on the same tree (monoecious). Male flowers are borne in slender pendant catkins, 5—10 cm long; female flowers (usually 1—3) are borne singly on short stout stalks in the leaf axils; the flower consists of a pistil with an inferior ovary and a 3-branched style. The base of each pistil is surrounded by a scaly cupule. Flowers bloom in early spring, just as the leaves emerge.
Fruit: An acorn (dry indehiscent fruit), 2—3 cm long by 1—2 cm wide, composed of an oblong nut subtended by a scaly cupule, 1.5—3 cm in diameter, which covers about ¼—½ of the base of the nut. The outer surface of the cupule consists of several tightly overlapping rows of small flat bracts. Cupule bracts are ovate with darker margins; the cupule base is flat. When immature, the nut of the acorn is green, but matures to a deep reddish-brown. Red oak acorns mature at the end of the second growing season, so first and second year acorns will be present on the same branch.
Habitat and Range: Sunny, moist to well-drained or dry upland slopes and ridges in deciduous and mixedwood forests. Native to temperate regions of eastern North America, the Canadian range of the northern red oak extends from Nova Scotia to northeastern Ontario. Northern red oak occurs throughout the southern half of the Algoma District.
Similar Species: The only other oak native to northern Ontario is the burr oak (Quercus macrocarpa Michx.), which can be distinguished by the rounded leaf lobes that lack bristle tips, and the cupule with upper scales thickened and prolonged into fleshy tentacle-like points, producing a fringe around the upper edge of the cupule.Back to species list