Blackjack Oak

Quercus marilandica

blackjack_oak_leaf.jpg

Illustration of blackjack oak leaf.
Blackjack oak (Quercus marilandica) leaf.
Paul Nelson
Family

Fagaceae (oaks)

Description

Blackjack oak is a small to medium-sized tree with a rounded, irregular crown; distinctive bark; and a tendency to retain dead branches on the middle to lower part of the trunk. It is well limbed along the entire length of the trunk.

Leaves are distinctively wedge- or bell-shaped; alternate, simple, bristle-tipped, leathery, and shallowly 3-lobed. Upper surface is dark green and shiny; lower surface is yellow-brown or yellow-green, with tan to brown hairs. Several leaves persist in winter.

Bark resembles alligator hide; blackish, very rough, with square or rectangular blocks.

Twigs are stout, stiff, grayish-brown, and densely hairy at first, smooth later; buds reddish-brown, narrowly cone-shaped, hairy.

Flowers April–May; in catkins.

Fruits September–October, a yellow-brown acorn, 1/2 to 1 inch long; cup deep, turban-shaped, red-brown, scales loose, hairy, covering 1/3 or 1/2 of the nut. Stalk very short. Acorns ripen in autumn of second year.

Size

Height: up to 60 feet, but rarely more than 30–40 feet.

blackjack_oak.jpg

blackjack oak
Blackjack Oak

blackjack_oak_acorn.jpg

Illustration of blackjack oak acorn.
Blackjack Oak Acorn
Blackjack oak (Quercus marilandica) acorn.

Oak _Quercus_spp_Flowers.jpg

Illustration of oak flowers and catkins, male and female.
Oak Flowers
All oak flowers are similar in appearance and emerge in early spring as the new leaves are expanding. Male and female flowers appear on the same tree.
Habitat and conservation

Occurs in acid soils over sandstone, chert, or igneous bedrock, on dry, often level uplands, slopes, savannas, and glades. Common in dry upland forests, especially ones that have been badly burned; often found growing on the poorest soils. Blackjack oak can withstand fire because of its thick, insulating bark and its ability to resprout. It is one of the first trees to occupy an area following a fire. Relatively short-lived, this slow-growing species cannot grow in shade. Occasionally grows along banks of streams. Also found in pastures, railroads, and roadsides.

image of Blackjack Oak Distribution Map
Distribution in Missouri

Scattered to common nearly statewide, but uncommon to absent in the western portion of the Glaciated Plains division and the southern portion of the Mississippi Lowlands.

Human connections

The wood has been used for railroad ties, fenceposts, charcoal, and fuel. Native Americans had many medicinal uses for oaks. Blackjack oak is a humble, unadmired tree, but we must also give credit to this rugged tree for living in places where few other trees will live.

Ecosystem connections

Jays, woodpeckers, turkey, mice, squirrels, raccoon, and deer eat the acorns. Innumerable organisms, from lichens to spiders, birds, snakes, squirrels, and raccoons, live in oak trees, in cracks in the bark, among the leaves, in the branches, or in hollow wood.