Bluejack oak

Quercus incana
Family: Fagaceae

Natural History
Leaves and branch of bluejack oak
Photo credit: Larry Korhnak, University of Florida

As the common name implies, the primary distinguishing feature of bluejack oak is the blue hue of the leaves. It also has a single bristle on the tip of the leaf. This is a characteristic that separates "red" oaks (with bristle tips) from "white" oaks. It ranges from southeastern Virginia to central Florida and as far west as southeastern Oklahoma and central Texas. Neighboring trees in its pine sandhill and hardwood hammock habitats include longleaf pine, turkey oak, southern red oak, and common persimmon.

The acorns are extremely valuable to wildlife such as deer, raccoons, squirrels, and quail. Sherman's fox squirrel prefers to consume bluejack oak acorns to other acorns, suggesting the acorns of this species taste better. Because this tree is often small and becomes a dense thicket, it provides important shelter and nesting sites for wildlife.

Bluejack oak is rarely used for timber, but it is an excellent wood for fuel, fence posts, and barbecue. It has also been used as pulpwood for making paper.


Identifying Characteristics

Habitat: Bluejack oak grows on well-drained sandy soils in pine sandhill and dry hardwood hammock communities.
Size/Form: Bluejack oak is a small tree that only reaches heights of 30' to 50'. It is often shrubby, with an irregular crown and short, crooked trunk.
Bark: The grayish black bark is thick with blocky furrows and rough ridges.
Leaves: The leaves are simple, alternately arranged, and may persist on the tree until spring. The leaves are 3" to 5" long by ½" to 1" wide. The oblong or narrowly elliptical shaped leaves usually have a bluish gray, leathery upper surface. The underneath surface is whitish gray with wooly fuzz. The leaf base and tip are rounded, but there is a single, prickly bristle on the tip. The margin is smooth.
Fruit: The acorns are ½" to ¾" long. The cap covers 1/2 to 1/3 of the acorn. Acorns mature in two growing seasons.



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Bark Acorns Insect gall on twig Leaves, showing the upper and lower surfaces
Photo credit: Larry Korhnak, University of Florida Photo credit: Larry Korhnak, University of Florida Photo credit: Larry Korhnak, University of Florida Photo credit: Larry Korhnak, University of Florida


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