Although some recent authors prefer to treat Quercus geminata as a variety of Q . virginiana , the two species are easily separable and rarely intergrade through most of the broad range in which they are sympatric. Apparently this is primarily because of habitat separation, but additionally Q . geminata flowers much later than Q . virginiana in any given geographic area. At the northern extreme of the range of Q . geminata , apparent intermediates with Q . virginiana are more common, possibly because flowering times of the two species overlap to a greater extent because of slower warming in the spring. Scattered intermediates also occur where the two species are sympatric on sands in coastal Mississippi.
The sand live oak (Quercus geminatus) is a small evergreen tree in the white oak group of oaks.It is native to the gulf coast plains of the southeastern United States, from Louisiana east to Florida and up the Atlantic coast as far as North Carolina.A remarkably hardy and drought-resistant tree, it grows in dry sandy soils of seacoast dunes, scrub, and high pine sandhills, mostly at low altitudes up to 200 m (600 feet).
The sand live oak is similar to the closely related live oak (Quercus virginiana), and the two sometimes interbreed, although they are discrete species. Both have dark brown, rough grooved bark, and cream-colored blossoms.The thick, leathery, elliptical-shaped dark green leaves of sand live oak have a fuzzy grey underside, which helps distinguish it from live oaks. The sides of the leaves also roll under towards the mid-vein, whereas live oak leaves are flat. Sand live oak (and live oak) trees produce separate male and female flowers.The male flowers occur in catkins that hang loosely from the branch. The very small female flowers have no petals, and emerge with new leaves right from the stem. In the spring sand live oak produces flowers several weeks after live oak does. This flowering time difference acts as a reproductive isolation barrier, retaining these two species as distinct even when they grow together.
In general, sand live oak trees are far shorter than Q. virginiana trees. The largest known individual lives stands 95 feet (30 m) tall, but individuals exceeding 30 feet (10 meters) tall are rare.Sand live oaks also differ from live oak in that they grow in various forms depending on the environment.When growing on wind swept coastal sand dunes, sand live oaks grow in short, shrubby, impenetrable thickets with their crowns rounded by wind.In scrublands, it grows as a shrub, no taller than 3 meters (10 feet) high.It grows larger in upland sand hills and pine woodlands, as individual trees or as a copse of multiple trunks connected as one individual underground.
A dominant part of the pine scrub and high pine habitats, sand live oak is adapted for the regular wildfires that sweep through these areas.Most (perhaps 80%) of the living part of the sand live oak tree exists underground.Once fire kills the portion of the plant above ground, the underground portion sends up shoots that regrow their vegetation.It is a fast-growing tree.
In the fall, sand live oak trees produce a large number of acorns, which often grow in pairs from the same stem.The genus epithet for this species, geminatus, derives from the Latin word for twins (although acorns also commonly occur singly and in bunches of three).The acorns are heavily prey upon as a plentiful food source of carbohydrates for many animal species including quail, jays, wood duck, sapsucker, wild turkey, black bear, raccoon, squirrel, and white-tailed deer. Seed caching animals (e.g. squirrels and jays) may serve to disperse the acorns but it is estimated that most get eaten.Sand live oak acorns are also prone to infestation by weevils (family Curculionidae).
Only rarely to acorns germinate and establish a seedling tree, despite the large number of acorns produced every year.Most sand live oak trees appear to develop as shoots from clones.Interestingly, acorns colonized by weevils may germinate at a higher rate than non-infested acorns.This is because during their development inside the acorn, weevils often do not damage the endosperm, and ultimately leave it viable to germinate.Animals reject weevil-infested acorns, and more often damage the endosperm of sound acorns, which thus do not survive to germination.
A diversity of bird species nest in its thick vegetation.In Florida scrublands, sand live oak is common and abundant and is an important part of the only known habitat of the endangered Florida scrub jay (Aphelocoma coerulescens) in peninsular Florida.
(Ainsworth et al. 2003; Christman 2007; Friedman et al. 2015; National Phenology Network 2016)
Quercus geminata, commonly called sand live oak, is an evergreen oak tree native to the coastal regions of the subtropical southeastern United States, along the Atlantic Coast from southern Florida northward to southeastern Virginia and along the Gulf Coast westward to southern Mississippi,[5] on seacoast dunes and on white sands in evergreen oak scrubs.[2]
Quercus geminata is placed in the southern live oaks section of the genus Quercus (section Virentes).[6]
A small- to medium-sized tree, the sand live oak is scrubby and forms thickets. The bark is dark, thick, furrowed, and roughly ridged. The leaves are thick, leathery, and coarsely veined, with extremely revolute margins, giving them the appearance of inverted shallow bowls; their tops dark green, their bottoms dull gray and very tightly tomentose, and their petioles densely pubescent, they are simple and typically flat with bony-opaque margins, having a length of 2–12 centimetres (3⁄4–4+3⁄4 inches) and a width of 0.5–4 cm (1⁄4–1+1⁄2 in). The male flowers are green hanging catkins. The acorns are small, 1–2.5 cm, oblong-ellipsoid or ovoid, and are commonly born in pairs on peduncles of varying lengths.[2][3]
In coastal Florida's evergreen oak scrub, the sand live oak is a ubiquitous and abundant species; the threatened Florida scrub-jay is found only in Florida scrub.[7][8] Live oaks, having characteristics of the sand live oak and the southern live oak (Q. virginiana), grow further inland. It is believed that these specimens are hybrids of Q. geminata and Q. virginiana.[2] While hybridization occurs between Q. geminata and Q. virginiana, the two species are genetically and morphologically distinct.[9] The Cuban oak, Q. sagrana, has been purported to be a hybrid[10][11] between the sand live oak and Q. oleoides, but recent evidence suggests that the Cuban oak is a separate species without hybrid origin.[12]
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Sand live oak at sunrise Quercus geminata, commonly called sand live oak, is an evergreen oak tree native to the coastal regions of the subtropical southeastern United States, along the Atlantic Coast from southern Florida northward to southeastern Virginia and along the Gulf Coast westward to southern Mississippi, on seacoast dunes and on white sands in evergreen oak scrubs.
Quercus geminata is placed in the southern live oaks section of the genus Quercus (section Virentes).
A small- to medium-sized tree, the sand live oak is scrubby and forms thickets. The bark is dark, thick, furrowed, and roughly ridged. The leaves are thick, leathery, and coarsely veined, with extremely revolute margins, giving them the appearance of inverted shallow bowls; their tops dark green, their bottoms dull gray and very tightly tomentose, and their petioles densely pubescent, they are simple and typically flat with bony-opaque margins, having a length of 2–12 centimetres (3⁄4–4+3⁄4 inches) and a width of 0.5–4 cm (1⁄4–1+1⁄2 in). The male flowers are green hanging catkins. The acorns are small, 1–2.5 cm, oblong-ellipsoid or ovoid, and are commonly born in pairs on peduncles of varying lengths.
In coastal Florida's evergreen oak scrub, the sand live oak is a ubiquitous and abundant species; the threatened Florida scrub-jay is found only in Florida scrub. Live oaks, having characteristics of the sand live oak and the southern live oak (Q. virginiana), grow further inland. It is believed that these specimens are hybrids of Q. geminata and Q. virginiana. While hybridization occurs between Q. geminata and Q. virginiana, the two species are genetically and morphologically distinct. The Cuban oak, Q. sagrana, has been purported to be a hybrid between the sand live oak and Q. oleoides, but recent evidence suggests that the Cuban oak is a separate species without hybrid origin.
