|All oaks, like this Post Oak, are members of the genus Quercus.|
Texas is home to dozens of native species of oaks, all of which are in the genus Quercus. These trees provide humans with ample shade in the summer and beautiful color in the fall, and they sustain many mammals and birds with their acorn fruit. But did you know that they are native host plants for dozens of butterflies and moth species, or the plants the female adults lay their eggs on for their caterpillars to eat? In turn, the caterpillars of these butterfly and moth species provide a critical food source for almost all of the songbirds raising broods in the spring. Three of the most productive native oak species in central Texas are the Texas Live Oak (Quercus fusiformis), Post Oak (Quercus stellata), and Bur Oak (Quercus macrocarpa).
|Texas Live Oak|
The Texas Live Oak is also known as Escarpment Live Oak, Hill Country, and Plateau Live Oak. Considered a semi-evergreen tree, the previous year’s leaves fall from the tree only when pushed out by newly emerging ones in early spring. It has a stately mature form and unparalleled longevity, reaching to 40 feet in height with large limbs that over time spread an appreciable distance from the main trunk. Firm textured leaves are oval to elliptical, 1 to 3 inches long, with young leaves having pointed lobes. Its acorns are spindle-shaped or fusiform, narrowed at the base and ¾ to 1 inch long.
The Texas Live Oak is a host plant for Oak Hairstreak (Northern form), Juvenal’s Duskywing, and Meridian Duskywing butterflies, as well as Grote’s Buckmoth, Eastern Buckmoth, and Delilah Underwing moths.
Also known Iron Oak and Cross Oak, Post Oak is a deciduous oak to 50 feet, coarsely-branched with a dense, oval crown. Its leaves are typically 3 to 5 inches long, with 4 pairs of lobes on each side, and the upper pair are often larger than the others, resembling a cross. Acorns are ¾ to 1.25 inches long. Post Oak is the most common oak throughout Texas, and its hard or iron wood is used for railroad ties as well as construction posts and timbers.
|'Northern' Oak Hairstreak|
It is a host plant for the Oak Hairstreak (Northern form) and White M Hairstreak butterflies, and the Polyphemus, Eastern Buckmoth, Scarlet Underwing, and Little Nymph Underwing moths.
|Bur Oak Acorn|
Bur Oak is one of our largest oaks, also known as Savanna Oak, Overcup Oak, Prairie Oak, and Mossy-cup Oak. A deciduous tree that can exceed 100 feet in height, its massive trunk supports heavy, horizontal limbs and lobed leaves up to 9 inches long. Its acorns are the largest of all native oaks, up to 1.5 inches wide, with much of the acorn enclosed in a coarsely scaled cup with a heavily fringed margin. Sometimes spelled Burr Oak, it is the northern most oak in the New World, extending farther north than any other oak species.
Bur Oak is the host plant for the Banded Hairstreak and Juvenal’s Duskywing butterflies, in addition to the Ilia Underwing, Imperial, and Greater Oak Dagger moths.
While Texas is known for its oaks, care must be taken in identifying and maintaining oak trees. Most all of the species can hybridize, occasionally making exact identification difficult, and several of them are susceptible to oak wilt disease. However, they are worth the effort from a human and wildlife standpoint, as they are Quercus with a purpose!