Sawtooth Oak, Quercus acutissima, is a deciduous, medium size (65’ tall) tree native to Asia. It was introduced into the U.S. and planted both as an ornamental and for wildlife (mainly deer and turkey) because of its rapid growth and relatively early acorn production; trees 5 – 10 years old can bear acorns. The acorns, however, are too large for turkey, and deer prefer acorns from the white oak group over those from the red oak group to which Sawtooth Oak belongs. This species has several other drawbacks. A study from the 1960s found that Sawtooth Oak acorns contained less protein, fat, and carbohydrates than eight native oak species that were tested. Unlike most native oaks, Sawtooth Oak drops its acorns in early fall; therefore, their acorns are unavailable in late Fall and Winter, when acorns are most valuable as a food source. This species also appears to be relatively short-lived and vulnerable to high winds unlike most native oaks. Sawtooth Oak is established in widely scattered locations across Louisiana. It is classified by the Louisiana Department of Wildlife and Fisheries as a Tier II invasive species defined as “currently causing moderately negative impacts on wildlife or natural communities in Louisiana”. Like most oaks, this species is likely spread by squirrels and blue jays that transport and cache acorns by burying them in the ground, but don’t recover a substantial number that grow into new trees. In this way, Sawtooth Oak spreads from initial planting sites into nearby forestlands, potentially displacing native plant species. It is no longer recommended for planting in the U.S. because of its potential impact on native ecosystems. Sawtooth Oak, however, is still promoted and sold to support turkey and deer populations on hunting lands.
Native Oak Alternatives
Responsible gardeners, landscapers, and property owners have a variety of native oak species from which to choose to fit most site conditions in Louisiana. Overcup Oak Quercus lyrata is medium in size (60 – 80’ X 25’), relatively slow growing, and adapted to tolerate poorly-drained soils. It occurs naturally in river bottoms, coastal plain swamps, and lowlands inundated for extended periods. Overcup Oak will do fine in upland landscapes as well as sites with poor drainage. Its leaves turn yellow in fall for an attractive display. Nuttall Oak Quercus texana (75’ X 60’) occurs at a slightly higher elevation in floodplains and bottomlands than Overcup Oak, but it too can thrive on well-drained sites as well as those with poor drainage. Leaves turn red to orange-red in fall. Nuttall Oak makes an excellent lawn, patio, or street tree; it can be limbed up to provide space beneath its branches for human activity, or in a naturalized area, for woodland shrubs and small trees. Swamp Chestnut Oak Quercus michauxii (60’ – 100’ X 45’) and Willow Oak Quercus phellos (100’ X 50’) are relatively large trees and occur naturally on still higher floodplain sites than Overcup Oak and Nuttall Oak. Both species are commonly cultivated in residential areas because of their high adaptability to almost any soil conditions. Swamp Chestnut Oak is long-lived, relatively slow growing, drought tolerant, and tolerates compacted soils better than most oaks. Fall color displays are yellow to vibrant red for Swamp Chestnut Oak and yellow to russet for Willow Oak. Shumard Oak Quercus shumardii and White Oak Quercus alba do not tolerate wet soils as do the oaks described above. Both occur naturally in moist upland forests and stream banks in Louisiana. Shumard Oak is relatively fast-growing and thrives in loamy, well-drained soils, but can tolerate short-term flooding as well as drought conditions. It is a handsome shade tree with attractive fall color displays of yellow to vibrant reds. White Oak is a popular, long-lived shade tree that does best in deep, moist, well-drained loamy soils. It does not tolerate poor drainage and alkaline soils and is particularly sensitive to root-zone disturbance from construction activity or replacing the forest duff ground cover around an established tree with turf. The fall foliage display is predominantly burgundy in color.
All of these native oaks are deciduous, bear wind-pollinated flowers March – May, and produce acorns, which are an important food for native wildlife. Whitetail Deer, squirrels and other small mammals, waterfowl, Blue Jays, and Wild Turkey depend on acorns during winter. Historically, acorns also were an important food for humans. Oaks are perhaps the most important link in the food chain between insects and birds. Oaks are the host of the larval (caterpillar) stage of more than 500 different species of moths or butterflies, the diets of young birds consist mostly of caterpillars, and a single nest of baby birds requires thousands of caterpillars during the few weeks between hatching and leaving the nest. Therefore, nesting success on your property likely depends on the presence of oaks. Now is an ideal time of the year to plant oaks and other trees on your property. All of these oak species, except Willow Oak, currently are available for sale at the ANPP greenhouse in Arnaudville.
Want to know more about the invasive plant problem in Louisiana? Check out the new content available on the Louisiana Native Plant Society (LNPS) website HERE. You will find background information about invasive plants and their threat to our native flora and fauna with a list, developed by the Louisiana Department of Wildlife and Fisheries, of the worst invasive plants in the state; also included is a list of steps that can be taken to counter this problem. Have a look and share this important information with others. Invasive plants are a very big problem for conservation and native plant communities, and it’s something everyone can act on. More information will be added to this LNPS webpage in the near future to include descriptions of the worst invasive plants and native plants that can be used as substitutes for these invasives.
By Lawrence Rozas
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