Oak, Blackjack

Quercus marilandica (Blackjack oak) is a small oak, one of the red oak group Quercus sect. Lobatae, but fairly isolated from the others. It is native to the southern and central United States. 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. Blackjacks in the Cross Timbers can grow from 50 to 60 feet (15 to 18 m) high with a trunk diameter of 16 inches (41 cm), but seldom reach more than 40 feet.

The broad, flat leaves LEAVES are from 4 to 10 inches (10 to 25 cm) in length and about the same width. They are simple, lobed leaves; some may seem unlobed, pinnately lobed with bristle tips, some without, not deeply lobed or shallow-lobed.

The thick, black BARK is deeply divided into rough, nearly square plates.

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, and is a good heat source for barbecues and wood-burning stoves, but not desirable in wood fireplaces because the heat causes “popping”, increasing the risk of wild fires.

The FRUIT or acorn is a cup without fringe, without long stalk, acorn no longer than 1″, scales not swollen, mostly flat, deeper cup, cup covers 1/2 of nut and the nut usually light brown .

Blackjack acorns provide food for both whitetail deer and wild turkey. Blackjacks may, however, cause tannic acid poisoning in cattle.