In the past, laurel oak and diamond-leaf oak have been considered by some to be two varieties or even separate species (11). Trees first recognized as laurel oak were on well-drained sandy banks of streams whereas diamond-leaf oak was found on poorly drained flat sites (5).
Burke concluded that laurel oak itself is of hybrid origin, intermediate between and derived from willow oak and water oak (2,3). His work is based on a leaf-shape index applied to seedlings grown from acorns collected on the North Carolina Outer Banks and at Chapel Hill, NC. He states that laurel oak is not found outside the ranges of the two supposed parental species. This would appear true based on most published maps showing the range of willow oak available in 1961 and 1963, when Burke's publications appeared. However, the range map for willow oak published in 1965 (14) shows willow oak to be absent in the southeastern half of Georgia and peninsular Florida where laurel oak grows in abundance, leaving some doubt that laurel oak is the hybrid between willow and water oak (14).
The following hybrids with Quercus laurifolia as one parent have been recognized (11): Quercus falcata Q x beaumontiana Sarg.), Q. incana Q. x atlantica Ashe), Q. laevis Q. x mellichampii Trel.), and Q. marilandica Q. x diversiloba Tharp ex A. Camus).
Laurel oak is a rapidly growing, short-lived, semi-evergreen tree. It can reach 148 feet (45 m) in height and 6.6 feet (2 m) in d.b.h. Darlington oak is slightly smaller at 131 feet (40 m) , and a geographic or climatic form in east Texas grows to only 30 feet (9.1 m) . Poor site conditions may be responsible for the smaller heights reported for Darlington oak.
Laurel oak develops a large, well-defined taproot on upland sands, but little else is known about its rooting habit . Roots of trees growing in wet areas are often buttressed, which provides stability in wet soils and may help aerate the root system .
Trees , tardily deciduous, to 40 m. Bark dark brown to black, ridges flat, furrows deep. Twigs red-brown, (1-)1.5-2.5 mm diam., glabrous. Terminal buds dark red-brown, ovoid to subconic, 2.5-6 mm, distinctly 5-angled in cross section, glabrous or with tuft of reddish hairs at apex. Leaves: petiole 1.5-5 mm, glabrous. Leaf blade rhombic or broadly elliptic to obovate, occasionally oblong or spatulate, 30-120 × 15-45 mm, thin, base attenuate or cuneate, rarely obtuse, margins entire with 1 apical awn, apex obtuse or rounded; surfaces abaxially glabrous, adaxially glabrous, veins raised. Acorns biennial; cup shallowly saucer-shaped to deeply bowl-shaped, 3.5-9 mm high × 11-17 mm wide, covering 1/4-1/2 nut, outer surface puberulent, inner surface pubescent at least 1/2 distance to rim, scale tips appressed, acute or attenuate; nut globose or ovoid, 8.5-16 × 10-16 mm, glabrate, scar diam. 6.5-11.5 mm.
Laurel oak is fire intolerant. It is frequently top-killed by even low-severity surface fires because it has relatively thin bark. It is also a poor natural pruner .
Many laurel oak stands such as those on hydric hammocks owe their existence to protection from fire . Hardwood hammocks are extremely susceptible to fire damage, especially during the dry season. A dry-season surface fire may burn the organic soil down to the bedrock .
If fire is suppressed, laurel oak expands from hydric hammocks into adjacent communities . Unlike the original hammock, expanding hammocks often have a dense saw-palmetto (Serenoa repens) understory. A dry-season fire in Myakka River State Park, Florida, killed many large laurel oaks in the expanding hammock but not in the original hammock. The dense saw-palmetto understory was, in part, responsible for the high mortality of laurel oak in the expanding hammock .
Information on the response of Darlington oak to fire was not available as of this writing (1992). Research is needed on the fire ecology of Darlingon oak.