Swamp white oak is the kind of tree you plant for not only your own enjoyment, but for the benefit of generations to come. It has a lifespan of over 300 years and a host of valuable characteristics, including beauty and outstanding wildlife value. As the common name implies, this stately, long-lived oak is found growing wild in low-lying and swampy areas — often in moist bottomlands or on river banks. But it fares just as well in urban or suburban settings, growing quickly in full to part sun and a range of dry to moist soils. Its young pyramidal form gradually spreads into a wide, irregular crown that provides shade and gorgeous fall color in shades ranging from yellow to crimson purple. The species name, bicolor, refers to the two-toned appearance of the green upper and white lower surfaces of the leaves. Swamp white oak has distinctive bark that is thick and furrowed. In winter, the older branches reveal attractive, peeling bark. The lower branches are pendulous and may need to be pruned if height clearance is needed. The tree is tolerant of occasional flooding, compacted soils, heat, and drought.
Swamp white oak is native to the midwestern US and is common throughout most of Ohio, save for the southeastern Appalachian counties. It’s a member of the white oak group, which is distinguished by leaves with rounded lobes and acorns that mature in a single growing season (red oak acorns take two seasons to mature). Many birds and animals depend upon the nutritious nuts for survival. According to the NY Botanical Garden, oak trees of North America produce more nuts in a year than all of that region’s other nut trees put together. One huge oak can drop 10,000 acorns in a mast year, which occurs every 3 to 5 years for swamp white oaks. Because masting takes so much energy, oak trees grow more slowly during these years. Despite many theories, scientists still don’t understand the factors that trigger mast years. Swamp white oak is susceptible to various insects and diseases, but none are serious. Chlorosis may occur when the pH level is too high.
Native habitats include swampy areas, lowlands, floodplains, and along streams and lakes. Site carefully, because swamp oak is difficult to transplant. Use in an area along a pond, a stream, or other wet or low sites. It’s a great choice for planting near streets or in yards as a shade specimen.
Plant Characteristics:
Grows 50-60’ and up to 100’ tall and 50-60’ wide.
Prefers 6+ hours of sun. Young trees tolerate more shade.
Prefers average to wet soils, but adapts to drier soils.
April to May, yellow catkins and spiky female flowers appear on the same tree, followed by light brown, 1-2” acorns with long, thick peduncles. They grow in clusters of 1-3 and ripen September–October. The pointy acorns are covered in fine, woolly hair and have scaly caps that cover half of the acorn.
Alternate, obovate leaves are 4-7" long with 6-10 pairs of large, rounded lobes. Upper surface is dark green while underside is soft, silvery white.
Mature bark is thick, black to grayish brown, and furrowed. Twigs are stout, short, reddish-brown, and smooth.
Wildlife Value:
In central Ohio, oak trees serve as host plants for 477 species of Lepidoptera larvae, including the gray hairstreak butterfly pictured here with its caterpillar. The myriad other insects it supports create a buffet for woodpeckers, warblers, flycatchers, and other insect-eating birds. Wood ducks, wild turkeys, ruffed grouses, white-breasted nuthatches, blue jays, common grackles, rusty blackbirds, brown thrashers, red-headed woodpeckers, and red-bellied woodpeckers eat the acorns, and many of these same species also nest and roost in nooks and crannies of oaks.
Medicinal, Edible and Other Uses:
Iroquois used swamp white oak for medicinal purposes.
Acorns, which supply eight essential amino acids, have been eaten as a staple food on four continents. They contain digestive inhibitors (tannins and phytic acid) that prevent absorption of the nut’s minerals. Native Americans soaked, sprouted, or fermented the nuts to reduce the tannins and phytic acid. Swamp white oak acorns don’t taste as bitter as red oak acorns, but they still need to be leached before being eaten.
The wood is used for general construction, furniture, cabinets, veneer, interior finishes, fence posts, and fuel.