Live Oak Tree
Although live oaks retain their leaves nearly year-round, they are not true evergreens. Live oaks drop their leaves immediately before new leaves emerge in the spring. Occasionally,senescing leaves may turn yellow or contain brown spots in the winter, leading many to mistakenly believe the tree has oak wilt, whose symptoms typically occur in the summer. A live oak’s defoliation may occur sooner in marginal climates or in dry or cold winters.
The bark is dark, thick, and furrowed longitudinally. The leaves are stiff and leathery, with the tops shiny dark green and the bottoms pale gray and very tightly tomentose, simple and typically flattish with bony-opaque margins, with a length of .75 – 6 inches (2 – 15 cm) and a width of .4 – 2 inches (1 – 5 cm), borne alternately. The male flowers are green hangingcatkins with lengths of 3 – 4 inches (7.5 –10 cm). The acorns are small, .4 – 1 inch (1 – 2.5 cm), oblong in shape (ovoid or oblong-ellipsoid), shiny and tan-brown to nearly black, often black at the tips, and borne singly or in clusters.
Depending on the growing conditions, live oaks vary from a shrub-size to large and spreading tree-size: typical open-grown trees reach 20 meters (60 feet) in height, with a limb spread of nearly 27 meters (80 feet). Their lower limbs often sweep down towards the ground before curving up again. They can grow at severe angles, and Native Americans used to bend saplings over so that they would grow at extreme angles, to serve as trail markers.
The southern live oak has a deep tap-root that anchors it when young and eventually develops into an extensive and widespread root system. This, along with its low center of gravity and other factors, makes the southern live oak extremely resistant to strong sustained winds, such as those seen in hurricanes.
The southern live oak grows in a wide variety of sites but has low fire-resistance and occurs most any place free from fire that is not too wet. They tend to survive fire, because often a fire will not reach their crowns. Even if a tree is burned, its crowns and roots usually survive the fire and sprout vigorously. Furthermore, live oak forests discourage entry of fire from adjacent communities because they provide dense cover that discourages the growth of a flammable understory. They can withstand occasional floods and hurricanes, and are resistant to salt spray and moderate soil salinity. Although they grow best in well-drained sandy soils and loams, they will also grow in clay. Live oaks are also surprisingly hardy. Those of southern provenance can easily be grown in USDA zone 7 and the Texas live oak (Quercus virginiana var. fusiformis), having the same evergreen foliage as the southern variety, can be grown with success in areas as cold as zone 6. Even with significant winter leaf burn, these trees can make a strong comeback during the growing season in more northerly areas, such New Jersey, southern Ohio, and southern Connecticut.