Black Oak | Glen Arboretum

Black Oak

Quercus velutina Lam.

Description

Black oaks reach maturity at about 60 feet tall with a 60-foot crown spread¹. These trees live up to 200 years². Leaves of black oaks contain 5-9 lobes with bristles on the ends¹. The depth of the sinuses between lobes varies and can be shallow or two-thirds away from the midrib¹. The leaves emerge in early spring with a reddish color from the velvety, 4 or 5 angled buds clustered at the ends of branches³. By summer the leaves are a glossy green color on the upper surface and yellow-green and slightly hairy on the lower surface. The petioles typically turn from green to yellow during late summer¹. The bark is deeply ridged and furrowed with a dark gray to black color on the exterior¹. The inner bark of a black oak is a yellow to deep orange color³. A mature black oak has a relatively thick basal bark that gives them moderate fire resistance⁴. Black oaks are monoecious, they bloom miniature female flowers during mid-spring and contain golden male catkins¹. Black oaks are wind pollinated, producing acorns that contain one seed in each². These acorns take 2 years to develop, with many maturing in late summer to early fall¹. The acorns are ½ to ¾ of an inch big with a rust colored bottom and a cap covering the top half³.

black oak acorn

Black oak leaves and acorn. @ P. Wray, Iowa State University¹⁰

The trunk of a Black Oak in Anne Arundel Co., Maryland (2/14/2013).

Bark of black oak. @ B. Hubick. 2013. Maryland Biodiversity Project¹²

Distribution

Black oaks are typically found in sunny locations³. They prefer well-drained, moist, acidic soils, but instead are commonly found in dry, poor soils due to their intolerance to shade¹. They are common in eastern deciduous forests⁵. They range as far north as southern Maine, as far south as Northern Florida, and as far west as southwestern Minnesota6. Black oaks are found throughout Maryland¹³, except in regions with serpentine soil⁶ such as found at Lake Roland Park and Soldiers Delight Natural Environment Area⁷.

{Native range of Quercus velutina}

Natural range of black oak. USDA¹¹

Wildlife Importance

Many mammals and birds eat the acorns of black oaks, some are wild turkeys, songbirds, chipmunks, squirrels, mice, black bears, opossums, and white-tailed deer^2,6. Even rabbits will eat the bark of saplings and the leaves of the seedlings². Black oak trunk cavities additionally provide shelter to animals such as birds, squirrels, and bats^2,6.

Economic Importance

Black oaks are commonly made into furniture, barrels, railroad ties, flooring, and interior finishes⁶. The yellow dye quercitron can be extracted from yellow to orangish interior bark of black oaks^3,6. By mixing quercitron with different metals bright yellows, tans, and olive-green dyes can be produced⁸. This natural dye was commonly used in the printing industry in the 1770s and by the 1790s was used to dye textiles⁹. This dye was also commonly used in the leather tanning industry².

Inner bark of black oak (above) and quercitron powder. Boston Museum of Fine Arts⁷

Threats

Black oaks can suffer from a range of threats including, gypsy moths, bacterial leaf scorch, obscure scale, oak horn gall, two-lined chestnut borer, and oak wilt^2,3. Black oak trees commonly decay making them structurally unsound³.

Interesting Facts

Black oak trees can grow over 100 feet tall, with one co-national champion tree reaching 131 feet in Michigan and another black oak reaching 84 ft tall in Connecticut³.
The diameter of black oak trees can be over 3.5 feet⁶.
Due to the species’ long, distinguished tap root, it is nearly impossible to relocate and transplant, and rarely cultivated as a landscape tree.
Because of frequent dieback of the shoots and resprouting, the roots of an oak tree may be 10-20 years older than the shoot¹¹.

References

Contributed by E. Stricker and E. Sobolewski

Towson University Glen Arboretum