Quercus geminata
(Quercus is an ancient name for oaks. Geminata, referring to the acorns, means twinned, as in Gemini.)
Fagaceae, the Oak Family
Talking with John and Dee Staley today got us all thinking about the Florida scrubby Oaks, given that Dee cultivates the acorns to replant to restore Scrub Jay habitat. A single Scrub Jay can cache more acorns than the best overachiever squirrel, and the Jays “like” Sand Live Oak for nesting. Around South Florida there are several small Oaks associated with dry sandy habitats. The main three locally are Myrtle Oak, Chapman’s Oak, and Sand Live Oak. Although they occupy similar sun-cooked, nutrient-poor, white sugar sand scrub, they are not closely related, and have conspicuous differences. Today’s featured species is the Sand Live Oak.
Sand Live Oak is kin to the big old venerable Live Oaks emblematic of the South. The two species are so similar that some botanists have classified them as variants of a single species. However, DNA, flowering-times, and different soil-water preferences suggest regarding them as distinct species. even if they do hybridize sometimes. The important thing is that they are more closely related to each other than either is to anyone else. Sister species, with Sand Live Oak probably having “branched off” of Live Oak long ago on the evolutionary tree of Oaks.
Sand Live Oak reveals its common ancestry with Live Oak, in my humble opinion, by occasionally forming “Live Oak” leaves. Generally the two have different leaves, those in Live Oak being flat, minimally hairy underneath, and elliptic to somewhat toothy and lobed. (Keep that elliptic, toothy, and lobed part in mind.)
Sand Live Oak differs by having its leaf blades long and narrow with the edges curled down strongly and a dense mass of felty hairs beneath. But, wait a moment, an occasional Sand Live Oak branch has “Live Oak” leaves: flat and lobed/toothy.
How weird. A throwback to its ancestral species? Sand Live Oak must have “Live Oak” genes, suppressed most of the time yet able once in awhile to break through. Who needs a DNA test to see the close relationship? Both species on the same tree.
I have some throwbacks to my ancestral species too. You know, useless fur, pointy canine teeth, tail(bones) aka my coccyx, you might say a suppressed carryovers from my own primate ancestors who had all that stuff for real.
To turn to a different species (see comments), here are two different Myrtle Oaks:
John Bradford
George Rogers
George Rogers
Dee Staley
Treasure Coast Natives 
Annie Hite
November 20, 2021 at 5:08 am
Thanks for including the links to articles about myrtle oak and Chapman’s oak. Anything to help distinguish the oak species I see in Jonathan Dickinson helps!
George Rogers
November 20, 2021 at 8:13 am
You do get all sorts of weird variations. Although Oaks are famous for hybridizing, I don’t think too much of that wide local variation is due to hybridization, as the three main species are not at all closely related. I’ve always found the Myrtle Oaks with toothed leaves (contrary to the guidebooks) very interesting in the local scrub, not sure how common leaves of that type are outside of Martin/PB counties. You don’t often see toothy Myrtle Oaks on herbarium sheets, which might mean they are rare outside of our area, or it may mean collectors shun “abnormal” specimens. Or both. See the two photos added at the end of the blog.
Harvey Bernstein
November 22, 2021 at 8:51 am
Maybe the individuals occasionally throwing aberrant leaves are the offspring of a hybridization event that occurred in the more recent past.
George Rogers
November 23, 2021 at 8:14 am
Possible, and hybridization was the first consideration in sizing up the “two species on one plant” situation, but the reason I do not think so are:
1. Hybrids usually show intermediacy, but the leaves on the “throwback” trees tend to be either “geminata” or “virginiana.”
2. A hybrid would ordinarily be expected to show the intermediacy throughout the plant, but in the present cases the trees are 99.9% “geminata” with scattered “virginiana” leaves/branchlets. The trees grow true to species, and then “something” causes localized loss of gene control and triggers the odd growth (fire? weather event? UV? gall insect? minor somatic mutation?)
3. The situation closely resembles the horticultural cases where a cultivar differs from its wild parent species, but occasionally pops out a branch resembling the parent species.
4. Although virginiana and its sister species geminata have been known to cross, such hybrids are unusual, and the plants in question live at the environmental extreme for geminata.
Here is he commentary from Flora North America relevant to virginiana-geminata hybridizing/forming intermediates:
“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.”