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Species Name:    Quercus virginiana 
Common Name:     

                 (Live oak)

 

I.  TAXONOMY

Kingdom Phylum/Division: Class: Order: Family: Genus:
Plantae Tracheophyta Magnoliopsida Fagales Fagaceae Quercus

Leaf detail of Quercus virginiana, live oak.  Photo courtesy of K. Hill, Smithsonian Marine Station.


Young live oak, Quercus virginiana
Photo courtesy of K. Hill, Smithsonian Marine Station.


Species Name:
Quercus virginiana P. Mill.

Common Name:
Live oak, Virginia oak, southern live oak, sand live oak, scrub live oak, Texas live oak.

Synonymy:
None

Other Taxonomic Groupings:
Subkingdom : Tracheobionta
Division : Magnoliophyta
Subclass : Hamamelidae

Potentially Misidentified Species:
None

Description:
Quercus virginiana is variable in its morphology depending on its location in the coastal strand. Those closest to scrub areas tend to be low-growing shrubs, while those further upland grow as large, spreading, long-lived trees which dominate the canopy. Trees growing in the open reach 15 m (approximately 50 feet) in height, with trunks of approximately 200 cm (79 inches). Crowns of these trees may reach a span of 46 m (150 feet) or more (Harlow et al. 1979; Harms 1990). Bark is longitudinally furrowed. Acorns are small and tapered in shape. Live oak limbs have a growth habit of first sweeping close to the ground, and later growing upward.


Live oak hybridizes with dwarf live oak, swamp live oak, and other species (Little 1979).

Live oak remains foliated nearly year-round, dropping its leaves and regenerating new growth within a few weeks during spring.

No consensus has been agreed upon regarding the taxonomic status of Q. virginiana. Some researchers recognize 3 separate species, while others recognize varieties rather than distinct species (Vines 1960; Little 1979; Harms 1990).


II.  HABITAT AND DISTRIBUTION

Regional Occurrence:
Live oak is an important component of maritime hammocks and scrub lands throughout its range from Virginia to Florida, including the Florida Keys. Westward, it ranges into Texas, where it is found to the east end of the Brazos River. West of the Brazos, Texas live oak (q.v. var. fusiformis) dominates (Simpson 1988).

The range of live oak corresponds to southeastern maritime strand communities (Oosting 1954) which lie southward of the 5.5 C (41.9 F) isotherm for average daily minimum temperatures in the coldest month of the year, typically January (Johnson and Barbour 1990).

IRL Distribution:
Live oak is widely distributed throughout the Indian River Lagoon system in maritime hammocks bordering coastal and inland wetlands. It is typically found in live oak-sea oats communities, live oak-slash pine communities, sand pine scrub communities, and the uplands of oak-pine forests. Live oak is somewhat more common in the northern portion of the lagoon around Cape Canaveral. South of this area, live oak and its associated species are gradually replaced by tropical shrubs (Myers and Ewel 1990).


III.  LIFE HISTORY AND POPULATION BIOLOGY

Age, Size, Lifespan:
Live oak is fast-growing under optimal conditions. Seedlings may reach 1.2 m (4 feet) in height within the first year, but growth rates taper off as age of the tree increases (Harlow et al 1979; Haller 1992). 70 year old trees may have trunks that measure as much as 54 inches in diameter (Van Dersal 1938).

Abundance:
Live oak is generally abundant throughout its range, and is often the dominant species in maritime hammocks. In the Indian River Lagoon, it is highly abundant on scrub lands, maritime hammocks, and upland forests. It is somewhat more abundant in areas of the lagoon north of Cape Canaveral.

Locomotion:
Sessile.

Reproduction:
Q. virginiana is monoecious. Small flowers are produced in spring during the growth period for new leaves. Pollen is dispersed by winds, generally during early April. Acorns are produced in abundance the following September (Harms 1990). Acorns generally fall to the ground during December, and are dispersed by animals.

Live oak sprouts from root collars and from roots. Dense clonal colonies sometimes result from this mode of reproduction, and have been observed up to 20 m (66 feet) in diameter.

Embryology:
Germination occurs shortly after seedfall in warm, moist soils.


IV.  PHYSICAL TOLERANCES

Temperature:
Live oak is extremely susceptible to freeze damage (Harms 1990). Its range thus corresponds to the 5.5 C isotherm along the east coast of the southern U.S.

Salinity:
Live oak is highly tolerant to salt spray conditions and often can be found growing where its roots are inundated with sea water at high tides. However, it does not withstand prolonged periods of saturation (Vince et al. 1989).

Physical Tolerances:
Live oak is able to withstand hurricane force winds and heavy rains and short periods of flooding, though not prolonged inundation (Vince et al. 1989). It is also tolerant of salt spray and high soil salinity.

     Diseases:
Diseases of live oak include live oak decline, a wilt disease caused by fungus that is a serious problem in Texas live oak, and perhaps other species as well. A defoliating disease called leaf blister, is also a problem for live oak species. Heartwood decay is able to infect trees, but typically, the sapwood in live oak is so strong that infected trees often remain standing (Harms 1990). Additionally, gall wasps may also colonize live oak, but apparently have little effect upon health of colonized trees (Haller 1992).


V.  COMMUNITY ECOLOGY

Trophic Mode:
Autotrophic.

Competitors:
Live oak is the dominant plant climax species in coastal forests in the northern portion of its range (Helm et al. 1991). It withstands competition due to its extreme salt tolerance and tolerance to shade.

Habitats:
Live oak grows well in moist to dry sites in scrub and maritime hammocks of the southeastern United States. It also shows good growth in clay and alluvial soils (Harms 1990).

Associated Species:
Live oak provides cover and shade for a wide variety of coastal species of birds and mammals. Acorns of live oak are an important food source for the Florida scrub jay, mallards, sapsuckers, wild turkey, black bear, squirrels and white-tail deer. Scrub jays, a threatened species, nest in live oak (Woolfenden 1973).

Epiphytes of live oak include mistletoe (Phoradendron spp.), ball moss and Spanish moss (Tillandsia usneoides). Spanish moss can be especially populous in live oak (Haller 1992).


VI.  SPECIAL STATUS

Special Status:
None.

Benefit in IRL:
Live oak is beneficial as habitat and for providing shade to many birds and small mammals. It is especially important to the Florida scrub jay as nesting habitat.

Economic Importance:
Live oak wood is strong and heavy, and has previously been used in ship building. However, it is now seldom utilized commercially (Harms 1990).


VII.  REFERENCES

Harlow, W.M., E.S. Harrar, and F.M. White. 1979. Textbook of dendrology. 6th
     
ed. McGraw-Hill, Inc. New York, NY. 510 pp.

Harms, W.R. 1990. Quercus virginiana Mill. live oak. In: Burns, R.M., and B.H.
      Honkala, technical coordinators. Silvics of North America. Vol. 2 Hardwoods.
      Agric. Handb. 654. U.S. Department of Agriculture, Forest Service.
      Washington, D.C. pp. 751-754.

Helm, A.C., N.S. Nicholas, S.M. Zedaker, S.T. Young. 1991. Maritime forests
      on Bull Island, Cape Romain, South Carolina. Bulletin of the Torrey Botanical
      Club. 118(2): 170-175.

Johnson, A. F. and M. G. Barbour. 1990. Dunes and maritime forests. In: Myers,
      R.L. and J.J. Ewel, eds. Ecosystems of Florida. University of Central Florida
      Press. Orlando, FL. pp. 430-480

Little, E.L. 1979. Checklist of the United States trees (native and naturalized).
      Agric. Handb. 541. U.S. Department of Agriculture, Forest Service.
      Washington, D.C. 375 pp.

Simpson, B.J. 1988. A field guide to Texas trees. Texas Monthly Press, Austin,
      TX. 372 pp.

Haller, J.M 1992. Quercus virginiana: the southern live oak. Arbor Age 12(5):30

Oosting, H.J. 1954. Ecological processes and vegetation of the maritime strand in
      the southeastern United States. Botanical Review. 20:226-262.

Van Dersal, W.R. 1938. Native woody plants of the United States, their
      erosion-control and wildlife values. U.S. Department of Agriculture,
      Washington, D.C. 362 pp.

Vince, S.W., S.R. Humphrey, R.W. Simons. 1989. The ecology of hydric
      hammocks: a community profile. Biological Rep. 85(7.26). U.S. Department
      of the Interior, Fish and Wildlife Service, Research and Development.
      Washington, D.C. 82 pp.

Vines, R.A. 1960. Trees, shrubs and woody vines of the southwest. University of
      Texas Press, Austin, TX. 1104 pp.

Woolfenden, R.P. 1982. Nesting and survival in a population of Florida scrub jays.
       Living Bird. 12:25-49.

 


Report by:  K. Hill, Smithsonian Marine Station
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Page last updated: Oct. 24,  2001