Mexican White Oak
Quercus polymorpha
Family: Fagaceae
OTHER NAMES
netleaf white oak, Monterrey oak
CHARACTERISTICS
This species has a narrow, upright form in youth that eventually develops into a rounded crown to 60 feet in diameter, plants get about 60-80’ tall, though in Arizona, 30-50’ is more likely. The irregularly lobed leaves emerge with a reddish-maroon color and gradually turn a deep blue-green. The bark is gray or brown. Flowers in spring, followed by acorns that ripen in summer.
This species was not known in the United States until 1992 when the small population in Texas was discovered.
GROWING CONDITIONS
AN EXPLANAITION OF TERMS USED
SUN full to part sun
WATER moderate to low water when established
SOIL tolerant, but good drainage and amendment are recommended
HARDINESS hardy to 0°F
BASIN middle
CONTAINER does ok in container but will not reach potential size
NUTRITION moderate to low
MAINTENANCE very little
Photo by diegoemiliohernandezserna, iNaturalist
Quercus polymorpha on Lady Bird Johnson Wildflower Center
ECOLOGY
Flowers in spring with inconspicuous, wind-pollinated flowers. Acorns ripen in fall. Oaks are wildlife keystone species hosting a mind-boggling number of insects. This brings in a vast array of substrate-insectivorous birds (birds that spend their time on these trees eating the insects). The acorns are important food for many birds and mammals (and some species eaten by people). The trees also provide important habitat for many birds and mammals. Almost all the oaks host a multitude of moths and butterflies including the following species:
Mexican-M Hairstreak (Parrhasius moctezuma)
Arizona Sister (Adelpha eulalia)
Short-tailed Skipper (Zestusa dorus)
Arizona Dull Firetip (Apyrrothrix araxes ssp. arizonae)
Burgess’s Sleepy Duskywing (Erynnis brizo ssp. burgessi)
Clitus Duskywing (Erynnis juvenalis ssp. clitus)
Meridian duskywing (Erynnis meridianus ssp. meridianus)
Scudder's Duskywing (Erynnis scudderi)
Mournful Duskywing (Erynnis tristis)
Oaks also host a diversity of insects that cause growths called “galls”. Galls are protective nests for the larvae of various insects (mostly tiny stingless wasps) to develop protected from pests. The have a diversity of shapes from giant ball-like growths, to small growths, on leaves or young stems. These galls do not harm healthy trees. Emory oaks that grow in riparian zones and get really tall are a favorite nesting site for owls and other raptors.
Oaks attract numerous other insects which, in turn, attracts canopy-gleaning birds.
ETHNOBOTANY
After some leaching, the acorns are edible. The wood is used for various building needs.
NATURAL DISTRIBUTION
Widespread in Mexico, Guatemala, and Honduras, and known from a single population in the United States (about 30 kilometres or 19 miles north of the Río Grande in Val Verde County, Texas) in a variety of habitats, including deep canyons in the Sierra Madre Oriental, riparian gallery forests, the margins of thorn scrub forest, tropical dry forests, the lower margins of montane oak–pine forests, and cloud forests.
TAXONOMY AND NAME
This plant is in the family Fagaceae, the beech family. There are 627 accepted species in the genus Quercus widely distributed in the northern hemisphere.
The genus "Quercus" is from Latin, meaning "oak". The species name, polymorpha, means “many forms” references this species’ ability to hybridize with just about any oak species.
This specimen is providing a lot of needed shade in a commercial setting in Nuevo Leon, Mexico. Photo by Adriana Nelly Correa Sandoval, iNaturalist
The foliage, photo by Cindy Chrisler, iNaturalist
This species has typical oak tassel-like flowers in spring. Photo by Francisco Valdes Perezgasga, iNaturalist
Developing acorn, photo by Benigno Gómez Garza, iNaturalist