Trees and Shrubs of the Eloise Butler Wildflower Garden

The Oaks of the genus Quercus account for more tree biomass than any other species in North America and Mexico (1). Scarlet Oak is a large deciduous tree, not native to Minnesota, but grows well here in certain conditions, usually reaching from 60 to 80 feet high. It has a rounded to irregular open crown with many dead branches and a lower trunk without the stubs of old branches. The largest known Scarlet Oak in the country is in Mercer NJ (2012) measuring 128 feet high, 112 foot crown spread, 201 inches in circumference and scoring 360 points.

The bark is dark gray to gray-brown on young stems, with smooth streaks, becoming blackish, thick, and furrowed into scaly ridges and plates, especially near the base of the tree. The inner bark is an orangish-pink.

Twigs are reddish-brown with light colored lenticels. Buds are reddish-brown also, plump, pointed and with light brown hair in the upper half. The twig has multiple terminal buds that are 5-angled in cross-section.

Leaves are alternate, elliptical to oval in outline, deeply divided, nearly to the mid-vein or at least half way, with 7 to 9 lobes, each lobe ending in bristle tipped teeth (awns) that number 18 to 50. The sinuses between the lobes are wide and round forming more than a half circle. Stalks are long and slender. Secondary veins of the leaf appear raised on both surfaces. The upper surface is a shiny green, the underside pale green with tufts of hair along the mid-veins. The leaf tip is pointed, the base is blunt (truncate) to slightly pointed (obtuse). Fall color is scarlet.

Flowers: The tree is monoecious, that is with separate male and female flowers. Male flowers are a yellow-green color, appearing in slender catkins, 2 to 4 inches long at the ends of the prior years growth. Each male flower usually has six stamens (can very from 2 to 12), which have long spreading white filaments when the flower fully opens. The female flowers are more reddish-green and appear as small slender spikes in the axils of new growth. They have 3 (to 6) carpels and styles that are slender and short. There are no petals; both sexes have the sepals fused together. Both flowers appear with the new leaves.

Seed: Acorn maturation is biennial; they are oblong to subglobose in shape, maturing to be 1/2 to 1 inch long, enclosed 1/3 to 1/2 in a turbinate to hemispheric cap, scales with broad glossy base, scale margins often strongly concave (tightly appressed); nut ovoid to subglobose, with 1 or more concentric rings of pits at apex. (Oak acorns are highly variable as to cap coverage and acorn size by geographic location) The nut is reddish-brown when mature. Caps do not expand as the acorn grows longer. The acorn matures in the second summer as do most species in the Quercus Sect. Lobatae - the Red Oak Group.

Habitat: Scarlet Oak grows from a deep taproot and spreading lateral roots. It preferred sites are dry upland slopes and ridges and is usually found in well-drained but generally poor soils. Full sun is required for a good shape. Scarlet Oak will hybridize with Northern Red Oak and Black Oak. Oaks should be pruned during the winter months, from October to March, to avoid open wounds where the Oak Wilt fungus can enter.

Names: The genus name, Quercus, is the Latin word for Oak. The species, coccinea, is from the Latin coccineus, for 'scarlet', the fall color of the leaves and the wood is also reddish. The author name for the plant classification from 1770 - ‘Münchh’ is for Otto von Münchhausen (1716-1774) German botanist, correspondent of Linnaeus. He described several species of oak. However, the common name was applied by Andre Michaux - see notes below.

Comparisons: Scarlet Oak will look similar to Black Oak, Q. velutina, but the acorns of Black Oak have loose hairy scales, especially at the fringe of the cup. Both have tufts of brown hair on the leaf underside at vein junctions. The leaves of Scarlet Oak are similar to Pin Oak, Quercus palustris, and Northern Pin Oak, Q. ellipsoidalis, and if you find a similar leaf in Minnesota in the wild it will probably be Northern Pin Oak which is the most closely associated oak speces. The acorn of Northern Pin is 1/2 to 1 inch long, 1/3 to 1/2 enclosed in a deep cup to top-shaped cap with tightly pressed scales which are finely hairy and have straight or slightly concave margins. The cap tapers abruptly to a stalked base. Another similar oak to compare is Northern Red Oak. Check the Oak Leaf Comparison Sheet.