Blackjack Oak

Blackjack Oak Quercus marilandicaThe blackjack oak (Quercus marilandica) is also known as the Jack oak, black oak, and barren oak. A small deciduous tree that grows 20 to 30 feet (maximum 90 feet) with a trunk diameter of 1 foot or less. It is similar to the post oak which also grows with blackjack oak, but the leaf lobes are more pronounced and not bristle-tipped.

blackjack oak tree
Blackjack Oak Tree - Photo by David Stephens,

Habitat: Found in upland woods of southeast Iowa

Hardiness: Varies with the species of oak tree, ranging from zones 3 through 9

Growth Rate: Slow to Moderate

Mature Shape: Broad, rounded

Height: Varies with species. Often maturing between 50 to 75 feet tall. Capable of growing upwards of 100 feet.

Width:40 to 70 feet. Varies with species

Site Requirements: Best growth in moist, well-drained soils. Adaptable to adverse soil conditions.

Flowering Dates: Spring

Seed Dispersal Dates: Fall

Seed Bearing Age: 20 years 

Seed Bearing Frequency: Acorns produced vary from year to year, with larger crops occurring during "mast year," every four to ten years.

Seed Stratification: Two to three months at 40° F or they can be set out in the fall for natural stratification and germination in the spring.

The leaves are 4 to 8 inches long, 3-lobed, bristle-tipped, taper to a rounded base, obovate in outline, thick petioles less than 1/2 inch long, top is dark yellow-green, beneath is paler with a tawny colored down.

Acorns are 3/4 inch long, with a shallow cup shaped like a goblet, and somewhat hairy. The nut is ovoid shape, yellow-brown, and striated. The twigs are thick, dark red-brown and hairy, and the trunk is almost all black with deep grooves and scaly plates.

The blackjack oak is known for growing in barren, dry, sandy, or clay soils. Its range extends from southeastern New York to southern Michigan and Nebraska, south to central Florida and eastern Texas. Blackjack oak can be found in the upland woods of northeast Iowa.

blackjack oak leaf
Blackjack Oak Leaf - Photo by Chris Evans, River to River CWMA,

Diseases that Affect Blackjack Oak

Insects that Affect Blackjack Oak

black jack oak fruit - acorns
Blackjack Oak Fruit - Photo by Franklin Bonner, USFS (ret.),

blackjack oak bark
Blackjack Oak Bark - Photo by Chris Evans, River to River CWMA,