Edward F. Gilman, Dennis G. Watson, Ryan W. Klein, Andrew K. Koeser, Deborah R. Hilbert, and Drew C. McLean
Introduction
This North American native oak reaches 40 to 60 feet in height and makes an attractive shade tree, with handsome scaly gray bark. The green, lobed leaves are deciduous but do not change color before dropping in fall. The insignificant, green, spring flowers are followed by small acorns, less than one-inch-long. The trunk often grows straight up through the crown with little pruning, and branches are well spaced along the trunk. This is one of the oaks which is not currently available in most nurseries, but it should be. Urban tree managers will want this oak once they find out about it.
Figure 1. Full Form—Quercus austrina: bluff oak
General Information
Scientific name: Quercus austrina
Pronunciation: KWERK-us oss-TRY-nuh
Common name(s): Bluff oak
Family: Fagaceae
USDA hardiness zones: 8A through 9B (Figure 2)
Origin: native to Atlantic and Gulf coastal states from southern Mississippi to southeastern North Carolina
UF/IFAS Invasive Assessment Status: native
Uses: reclamation; street without sidewalk; shade; specimen; parking lot island > 200 sq ft; tree lawn > 6 ft wide; highway median
Figure 2. Range
Description
Height: 40 to 60 feet
Spread: 35 to 50 feet
Crown uniformity: symmetrical
Crown shape: oval, round
Crown density: open
Growth rate: moderate
Texture: medium
Foliage
Leaf arrangement: alternate
Leaf type: simple
Leaf margin: lobed, entire
Leaf shape: obovate
Leaf venation: pinnate
Leaf type and persistence: deciduous
Leaf blade length: 1 to 6 inches
Leaf color: dark green and shiny on top, paler green underneath
Fall color: copper, yellow, orange
Fall characteristic: showy
Figure 3. Leaf—Quercus austrina: bluff oak
Flower
Flower color: brown
Flower characteristics: not showy
Fruit
Fruit shape: round, oval; oblong
Fruit length: ½ to ¾ inch
Fruit covering: dry or hard acorn; cap has tight brown scales, is bowl-shaped, and covers the top 1/3–½ of the shiny nut
Fruit color: tan orbrown
Fruit characteristics: attracts squirrels/mammals; not showy; fruit/leaves a litter problem
Fruiting: mid to late fall
Trunk and Branches
Trunk/branches: branches don't droop; showy; typically one trunk; no thorns
Bark: whitish, scaly from about 1/3 of the way up the trunk and above, and with broad ridges
Pruning requirement: little required
Breakage: resistant
Current year twig color: green, brown
Current year twig thickness: medium
Wood specific gravity: unknown
Figure 4. Bark—Quercus austrina: bluff oak Credit: Gitta Hasing
It would be well suited for planting in parking lots or along streets and boulevards where there is plenty of space for crown development. A row of bluff oaks planted on 30-foot centers lining each side of a street make a wonderful site. The medium-textured leaves make this oak stand out from other oaks. Upright to horizontal branching habit make this an easy tree to prune for vehicular clearance beneath the canopy.
Bluff oak should be grown in full sun on well-drained soil, and has good drought-tolerance.
Quercus durandii var. austrina is a synonym.
Propagation is by seed.
Pest and Diseases
No pests or diseases of major concern.
Reference
Koeser, A. K., Hasing, G., Friedman, M. H., and Irving, R. B. 2015. Trees: North & Central Florida. Gainesville: University of Florida Institute of Food and Agricultural Sciences.
