This tree is typically 60-80' tall at maturity, developing a straight
trunk about 2-3½' across and an ovoid to obovoid crown. In open sunny
areas, the trunk is shorter and the crown is more broad, while in
forested areas the trunk is longer and the crown is more narrow.
Depending on the maturity of a tree, trunk bark is brown, gray-brown,
or gray, rough-textured, and developing either irregular furrows with
flat ridges or large flaky scales. Branch bark is similar to trunk
bark, but more smooth, while the smooth twigs are brown or
gray, smooth, and covered with scattered white lenticels.
Alternate leaves about 4-7" long and 2½-4½" across occur along the
twigs and young shoots. They are usually obovate (less often broadly
elliptic) with 4-8 pairs of lobes along their margins. These lobes are
shallow to moderately deep and they are either rounded or taper to
blunt tips. The sinuses between the lobes are concave or bluntly cleft.
The upper leaf surface is medium to dark green and glabrous,
while the lower surface is whitish green to white and densely covered
with short white hairs that are stellate and fine-textured. The leaf
texture is rather leathery and stiff. The petioles are ½-1" long, light
green or light yellow, and either glabrous or short-pubescent.
White Oak is monoecious, producing separate male (staminate) and female
(pistillate) flowers on the same tree. The male flowers are produced
along drooping catkins about 2-4" long; the male flowers are sparsely
distributed along these catkins in small clusters. Each male flower
(about 1/8" or 3 mm. in length) consists of several stamens that are
within hairy floral bracts. The female flowers are produced from
the axils of leaves in clusters of 2-4. Each female flower (about 1/8"
or 3 mm. in length) consists of an ovary with usually 3 stigmata; it is
embedded within an involucre consisting of hairy floral scales.
The blooming period occurs from mid- to late-spring and lasts about 1-2
weeks. The flowers are cross-pollinated by wind. Afterwards, fertile
female flowers develop into acorns that become ¾-1" long and ½-¾"
across at maturity during the autumn of the same year. Usually, only
1-2 acorns develop near the tip of a long peduncle about ½-4" long,
while the pedicel of each acorn is very short (less than 1/8" or 3 mm.
The cup of a mature acorn is tan-colored or light gray, while its body
is brown; the cup extends to about one-third of the length of an
acorn. The scales of the cup are somewhat recurved and pointed,
rather than appressed together. The white acorn meat is mildly bitter.
The woody root system is shallow to moderately deep and widely
spreading. During the autumn, the deciduous leaves become brownish
yellow, sometimes with patches of orange and red.
The preference is full sun, wet to mesic conditions, and soil
containing some combination of loam, clay, silt, or sand. Soil pH
should be non-alkaline. Both compaction of the soil and temporary
flooded conditions are tolerated. Individual trees can produce acorns
in 20-30 years and they may live 300-350 years. Mature acorns will
germinate shortly after they have been placed in moist ground.
The native Swamp White Oak is
occasional in most areas
of Illinois, except in the NW section of the state, where it is rare or
absent (see Distribution
). Habitats include floodplain woodlands,
edges of swamps, borders of streams, sloughs, poorly drained
upland flats, and edges of vernal pools in wooded areas.
Swamp White Oak is found with miscellaneous deciduous trees in poorly
drained areas, including Green Ash, American Elm, Red Maple,
Silver Maple, American Sycamore, Eastern Cottonwood, Pin Oak, Bur Oak,
Shellbark Hickory, Sweet Gum, Black Gum, and Black Willow.
Sometimes Swamp White Oak is cultivated as a landscape tree in parks
and residential areas.
The value of Swamp
White Oak and other oaks (Quercus
) to wildlife is high. The
following leafhoppers prefer Swamp White Oak as a host plant:
and Eratoneura mirifica
leafhoppers that feed on this tree include Eratoneura carmini
and Eratoneura solita
Other insects feeders include the aphids Myzocallis
, and the treehoppers Atymna helena
. The larvae of a large number of beetles
bore through the
wood or bark of this and other oaks. These species include Eucrada
(Anobiid Beetle sp.), Arrhenodes minuta
(Oak Stem Borer), Goes
Pruner), and Oberea
(Oak Sprout Pruner); see the Wood-Boring Beetle
for a more complete list of these species. Other insect
include several leaf beetles (Metachroma
etc.), Brachys ovatus
(Oak Leaf Miner) and other Brachys
, larvae of the weevils Attelabus bipustulatus
, the plant bugs Ceratocapsus modestus
(Oak Lace Bug), and the larvae of
various gall wasps (Cynipidae). The caterpillars of Hairstreak
butterflies, Duskywing skippers, and numerous moths also feed on the
other parts of oaks (see Lepidoptera Table
These various insects are an attractive
source of food for woodpeckers, warblers, flycatchers, and other
insectivorous birds. Acorns are an important source of food for many
birds and mammals. Acorn-eating birds include the Wood Duck, Wild
Turkey, Ruffed Grouse, Ring-Necked Pheasant, Monk Parakeet,
White-Breasted Nuthatch, Blue Jay, Common Grackle, Rusty Blackbird,
Brown Thrasher, Red-Headed Woodpecker, and Red-Bellied Woodpecker.
Acorns are also eaten by the Black Bear, Raccoon, White-Tailed Deer,
White-Footed Mouse, and various tree squirrels. There is even a record
of a turtle, Trionyx
(Spiny Softshell), eating acorns (Ernst
et al., 1994).
the tree silhouette, tree trunk, and leafy twigs with acorns were
taken by Paul Showers (Copyright © 2011) in NE Illinois. The photograph
of the leaf undersides was taken by John Hilty near a stream at
Meadowbrook Park in Urbana, Illinois.
Where their ranges overlap, this oak sometimes hybridizes
with the Bur Oak (Quercus
) and Basket Oak (Quercus
) – all of these oaks prefer bottomland habitats.
Oak can be distinguished from White Oak (Quercus alba
Bur Oak by
the more shallow lobes of its leaves and their whitened undersides. It
differs from Basket Oak by having fewer lobes along the margins of its
leaves. Swamp White Oak can be distinguished from these and other oaks
by the long peduncles (½-4" in length) of its acorns. Other oaks have
shorter peduncles. The wood of Swamp White Oak
is relatively heavy, strong, light brown, fine-grained, and
rot resistant. It has been used in the construction of furniture,
cabinets, interior finishing, flooring, barrels,
kegs, crates, boat hulls, rail ties, and fence
posts. Compared to White Oak, however, its wood tends to be
more knotty from the persistence of lower branches. Oak trees are hosts
to many parasitic and symbiotic fungi. Examples of bracket fungi that
are found on standing or fallen trunks include Inonotus hispidus
(Shaggy Bracket), Daedalea
(Oak Mazegill), and Fistulina
(Beefsteak Fungus). In addition, Evernia prunastri
Lichen) and other lichens are often found on oak trees.