As promised in my “The Little Oaks Part I”, here we will explore two more species of shrubby oaks; these are little, I’m talking, like three feet max. The two species we will examine today are running oak (Quercus pumila) and dwarf live oak (Quercus minima).
Running Oak
Quercus pumila
Appropriately named, running oak or runner oak spreads via underground runners. This dwarf oak will hardly ever exceed more than three feet in height! It can be found throughout the southeastern United States, but prefers dry, sandy soils.
In the fall, running oak will lose its leaves, a key difference from the dwarf live oak. When the leaves come back in the spring, there are a few things to note. They are relatively flat, though often rolled under (revolute) with smooth (entire) margins. Running oak leaves can be anywhere between one to four inches long and just under a half inch to over an inch and a quarter wide. Leaves have little to no hairs on the shiny, dark green upper leaf surface, but lots of reddish-brown hairs (pubescence) on the leaf underside.
If present, acorns are also pubescent on the inner and outer surfaces. The cap covers between 1/3 to ½ of the nut and doesn’t get to be much bigger than about ½ in wide or long. One characteristic to note about running oak acorns is that they sit directly on the twig, or what we call sessile.
Dwarf Live Oak
Quercus minima
Okay, so names aren’t everything because the dwarf live oak can also “run” by underground rhizomes, forming three feet tall thickets. But, unlike the running oak, dwarf live oak is evergreen. It is also reported to be semi-evergreen or what we refer to as tardily deciduous, meaning it will lose its leaves later in the winter or early spring. The unique part about being tardily deciduous is that we won’t really notice since new growth is also starting at this time.
Leaves of dwarf live oak are between ¾ of an inch to almost five inches long and just under a quarter inch to two inches wide. They are also quite variable in shape. Dwarf live oak leaves tend to be more lobed or have irregular teeth compared to the smooth leaf margins of running oak leaves. Also, if lobes are present, they tend to be tipped. These wavy leaves are glossy dark to light green on top with a paler green underneath due to whitish pubescence.
Dwarf live oak acorns are about ½ inch to an inch long and up to ½ inch wide. Acorns are a shiny dark green (turning dark brown when mature) and lack hairs. One other thing to note about the acorns of these two species is that dwarf live oak acorns sit suspended from the twig, sometimes as much as an inch!
As with any oak species, acorns provide an excellent source of food for wildlife. In the case of these very small, shrubby oaks, they also provide an excellent source of cover. Both of these oak species serve as host plants for two species of hairstreak butterflies: the red-banded hairstreak (Calycopis cecrops) and the white-M hairstreak (Parrhasius m-album).
Information Sources: https://plants.usda.gov/core/profile?symbol=QUPU80 https://www.wildflower.org/plants/result.php?id_plant=QUPU80 http://oaks.of.the.world.free.fr/quercus_pumila.htm http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233501076 https://en.wikipedia.org/wiki/Quercus_minima https://www.regionalconservation.org/beta/nfyn/plantdetail.asp?tx=Quermini https://www.wildflower.org/plants/result.php?id_plant=QUMI2 https://plants.usda.gov/core/profile?symbol=QUMI2 http://oaks.of.the.world.free.fr/quercus_minima.htm http://florida.plantatlas.usf.edu/Plant.aspx?id=2589 Flora of Florida, Volume II, Dicotyledons, Cabombaceae through Geraniaceae by Richard P. Wunderlin and Bruce F. Hansen.
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