August Tree of the Month-Swamp White Oak
Soaring up to 60 ’ and living up to 300 years, the swamp white oak, Quercus bicolor, is one of Missouri’s grandest native trees. Like other oaks in the White Group, it has thick, glossy green leaves with pale undersides (hence the specific epithet, bicolor), with rounded lobes, unlike the Red Group, which has tiny spines on the lobes.
Swamp whites are named for the moist, wet areas they are often found in along streams, riverbanks, and lowlands. Despite this, they are quite drought-tolerant once established.
Identifying swamp whites is easy thanks to the brown acorns in fall that follow the spring catkins. The acorns typically grow in pairs at the end of a long peduncle, or stalk, with a good crop every 3 to 5 years that wildlife such as woodpeckers, blue jays, wild turkeys, deer, bears, and small mammals enjoy.
Another good ID feature is that mature swamp whites usually have large, whitish patches indented into the otherwise gray bark. This is called Smooth Patch Disease, or sometimes White or Bark Patch Disease, and is caused by a generally harmless fungus; it’s a cosmetic issue and won’t kill the tree. Branches and stems can be very rough and flaky.
On a more serious note, Chlorosis (yellowing of the leaves while the veins remain green) often occurs when soils are not properly acidic. Anthracnose, rust, blight, galls, canker, and leaf spot are also common. Pests include borers, leaf miners, oak lace bug, and oak mite.
The swamp white, like many other native oaks, is a keystone plant, hosting up to 500 species of moths and butterflies and providing ample ecological benefits from food and pollen to shelter.
What I love about this plant;
-It’s native!
-Keystone plant that supports ample wildlife and pollinators.
-Majestic, long-lived tree
-Great shade tree.
What’s not so great;
-Can get large-give it room above and around.
-Acorns can be messy. Not a great choice for next to walks, drives, or patios, etc.
– Chlorosis (yellowing of the leaves while the veins remain green) can occur in alkaline soils.
-Anthracnose, rust, blight, galls, canker, and leaf spot. Pests include borers, leaf miners, oak lace bug, and oak mite.
-Smooth Patch Disease; large, whitish patches on bark caused by a fungus that is cosmetic and won’t kill the tree.
-Comments or questions? Email Garden-Lou at gardenloustl@gmail.com
Words and photos by Jo Batzer
© Jo Batzer, garden-lou.com-2026, All rights reserved.
