Information on the Live Oak Tree

Overview

The romantic dreams of the Old South wouldn't be complete without the massive live oak. Appreciate the architectural beauty of the branches while enjoying the refreshing shade cast by the evergreen leaves. Not particularly fond of subfreezing winter temperatures, live oak grows and looks best in USDA hardiness zones 8 through 11.

Origins

Live oak hails from the coastal plain of the southeastern United States from southeastern-most Virginia to Florida's Keys and westward to the Brazos River in Texas. It is considered a climax forest species, becoming the final and largest plant in succession in the natural ecosystem.

Description

A dominant evergreen tree at maturity, live oak grows 40 to 80 feet tall and 60 to 100 feet wide. Having a rounded canopy when young, with age its massive branches spread far and wide, often with very low or ground-touching branches. Its gray bark is cross-checkered into corky blocks with black crevices. The glossy dark green leaves feel like leather and have recurving edges and a gray-green underside. Shedding yellow pollen heavily in spring, the female oak flowers develop into dark brown to black acorns enclosed one third by a cap. They are no larger than 1 inch in size. An evergreen, it sheds its oldest leaves year-round, but more heavily in spring before new leaves flush.

Cultural Requirements

Growing well in full sun to partially shaded locations, live oak grows well in sandy, loamy and well-draining clay soils. Moist soils rich in organic matter and having an acidic pH (less than 8.0) allows the tree to grow its strongest and fastest. Tolerant of heat, high humidity, salt spray and wind, live oak is among the trees that often survives tropical storms. As this tree become enormous, do not plant it too closely to sidewalk or roads that will either be affected by its root system or low-growing branches. It remains highly sensitive to frost and subfreezing temperatures, which initially only causes defoliation.

Considerations

Like most oaks, the live oak does not cope well with disruption during transplanting. Thus, live oaks are grown in containers so that the least amount of root disturbance occurs when being planted. Alternatively, landscapers often root prune live oaks dug from a nursery field before the transplanting event. While many attest to live oaks being slow growing, their growth hastens considerably when irrigated and supplied with an organic-rich soil. Rufino Osorio, native plant expert from Florida, mentions that root-bound containerized live oaks will falter in the landscape initially because their constricted root systems must first break out and penetrate the surrounding soil before producing more branch growth. The bromeliad Spanish moss (Tillandsia usneoides) does not harm a live oak, and some people erroneously call this stringy plant a fungus or parasite. Live oak decline, a wilt disease caused by Ceratocystis fagacearum, is a serious threat to Texas live oak (Quercus virginiana var. fusiformis), which is a natural form of the live oak that naturally grows west of the Brazos River in Texas.

Similar Species

Sand live oak (Quercus geminata) is a smaller, much slower growing oak that resembles the live oak. It perhaps makes a better choice for shade in residential landscapes or street medians lacking room or irrigation. Laurel oak (Quercus hemisphaerica) grows also as a stately large shade tree but usually drops half of its leaves in winter. Laurel oak's leaves do not have a woolly, gray-green underside like those of the live oak. Moreover, the swamp laurel oak (Quercus laurifolia) bears diamond-shaped leaves and tolerates much wetter soils.

Uses

Historically, Native Americans pressed live oak's acorns to make an oil that resembles olive oil. The dense heavy wood was also once used in ship-making. Today, live oak's role remains only as an ornamental shade tree.

Keywords: coastal live oak, Quercus virginiana, Southern shade trees, Spanish moss

About this Author

James Burghardt has written for "The Public Garden," "Docent Educator," non-profit newsletters and for horticultural databases, becoming a full-time writer in 2008. He holds a Master of Science in public horticulture from the University of Delaware and studied horticulture and biology in Australia at Murdoch University and the University of Melbourne.