Quercus marilandica

Blackjack Oak
Dormant blackjack in the Cross Timbers of Lincoln County, Oklahoma
Scientific classification
Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Fagales
Family:	Fagaceae
Genus:	Quercus
Species:	Q. marilandica
Binomial name
Quercus marilandica Muenchh.

The Blackjack oak (Quercus marilandica) is a small oak, one of the red oak group Quercus sect. Lobatae, but fairly isolated from the others. It is native to the eastern United States, from southern New York (Long Island) south to northern Florida and west to southeastern Nebraska and central Texas.

Line drawing of blackjack leaf and acorn

It is a small deciduous tree growing to 15 m tall, with bark cracked into rectangular black plates with narrow orange fissures. The leaves are 7-20 cm long and broad, and typically flare from a tapered base to a broad three-lobed bell shape with only shallow indentations. They are dark green and glossy above, pubescent underneath, and often remain attached to the twigs through the winter after turning brown in the fall. The acorn is small, 12-20 mm long and 10-18 mm broad; like other red oaks, it takes 18 months to mature.

The Blackjack oak grows in poor, thin, dry, rocky or sandy soils where few other woody plants can thrive, usually on low ground, from sea level up to 900 m altitude. It does not have the beautiful form of many oaks, but is nonetheless a valuable tree for growing in problem sites. It is sometimes an understory tree in pine stands on sandy knolls in the southeastern US. Along the coastal plain of New Jersey the probability of finding this species is increased in relatively sunny, open areas such as those near coastal salt marshes. It often occurs near Scarlet and Post Oaks as well as Pitch Pine; understory companions include Winged Sumac, Bracken, Sweet Fern, and Bayberry.

A variety, Quercus marilandica Münchhausen var. ashei Sudworth (D. M. Hunt 1989), grows in the western portions of its range—northern Texas, Oklahoma, and into southern Kansas. In this area, Blackjack, along with Post oak, forms a semi-savanna area composed of forested strips intermixed with prairie grass glades along the eastern edge of the southern Great Plains. This semi-savanna is known as the Cross Timbers. Blackjacks in the Cross Timbers can grow from 50 to 60 feet (15-18 m) high with a trunk diameter of 16 inches (40 cm), but seldom reach more than 40 feet (12 m). The leaves are from 4 to 10 inches (10-25 cm) in length and about the same width. Blackjack acorns provide food for both whitetail deer and wild turkey. Blackjacks may, however, cause tannic acid poisoning in cattle.

Uses

The wood is very dense, so much so that it will rapidly dull chainsaws. The density of the wood causes a very hot flame when burnt, making Blackjack oak wood the preferred fuel for slow-cooked (Carolina style) pork barbecues and a good heat source for wood-burning stoves, but not desirable in wood fireplaces because the heat causes "popping", increasing the risk of external fires.

References and external links

• Flora of North America: Quercus marilandica
• Quercus marilandica images at bioimages.vanderbilt.edu
• Quercus marilandica (L.) Muenchh. var. ashei Sudworth - USDA. (accessed March 4, 2007)
• Hatch, Stephan L., Jennifer Pluhar (eds.). Texas Range Plants. College Station: Texas A&M University Press, 1999. ISBN 0-89096-538-2
• Phillips, George R., Frank J. Gibbs, Wilbur R. Mattoon (eds.). Forest Trees of Oklahoma. Oklahoma City: State Board of Agriculture Forestry Division, 1973.