smooth,
while twigs are yellowish brown to purplish brown and glabrous with
scattered white lenticels (air pores). Young shoots are light green and
pubescent. Alternate leaves occur along the twigs and young shoots. New
leaves are pubescent, but they become hairless later. Mature leaves are
4-7" long and 2-4½" across; they are broadly elliptic or obovate in
outline and pinnatifid with 3-5 pairs of deep to medium lobes. The
lobes have round tips and round sinuses; sometimes a few small
secondary lobes are present. The upper surface of mature leaves is
medium green and glabrous, while the lower surface dull light green or
gray-green and hairless (or nearly so). The leaf bases are narrow and
wedge-shaped (cuneate). The petioles are ¼-¾" long, light green to
yellow, and glabrous. Because of the short petioles and their stiff
texture, the leaves are resistant to fluttering in the wind. Because
White Oak is monoecious, separate male (staminate) and female
(pistillate) flowers are produced on the same tree. Male flowers are
produced in greenish yellow catkins about 2-3½" long that develop near
the tips of last year's branches. Individual male flowers are 1/8" (3
mm.)
across or less, consisting of an irregularly lobed calyx and several
stamens. Greenish red female flowers are produced at the tips of new
shoots on very short peduncles (less than 1/8" or 3 mm. long).
Individual female
flowers are 1/8" (3 mm.) across or less, consisting of a pubescent
calyx that
surrounds an ovoid ovary with 3 stigmata. The blooming period occurs
from mid-
to late spring for about 1-2 weeks. The flowers are cross-pollinated by
the wind. Fertile female flowers are replaced by acorns that become
mature by the fall. Mature acorns are ½-1" long, consisting of a
shallow cap and a nut. The cap is light tan or light gray with
warty scales; it extends downward to about one-fourth the length of the
acorn. The nut exterior is greenish brown to light brown, ovoid in
shape, and glabrous, while the meat of the nut is white and usually
slightly bitter. The root system consists of a taproot and widely
spreading lateral roots. The deciduous leaves become reddish purple or
brown during the autumn; a few dead leaves may persist on the tree
during the winter.
Cultivation: The preference is full or partial sun, mesic to dry-mesic conditions, and deep loamy soil. However, this oak also adapts to other kinds of soil, including those that contain silt-loam, sandy loam, clay-loam, and gravelly or rocky material. This slow-growing tree can live up to 600 years. Because of its long taproot, it is sometimes difficult to transplant. Locations prone to flooding should be avoided.
Range & Habitat: The native White Oak is a common tree that is found in every county of Illinois (see Distribution Map). It is the state tree of Illinois. Habitats include upland woodlands, well-drained areas of bottomland woodlands, sandy woodlands, bluffs, wooded slopes, savannas and sandy savannas, edges of limestone glades, and high riverbanks above the flood zone. White Oak is found in wooded areas of varying quality; sometimes it is a dominant or codominant canopy tree. White Oak is slowly being replaced by more shade tolerant trees, particularly Sugar Maple (Acer saccharum), because of the suppression of fire, to which it is moderately resistant. White Oak is also cultivated as a landscape tree and it is often found in city parks.
Faunal Associations: Caterpillars of the butterflies Calycopis cecrops (Red-Banded Hairstreak), Fixsenia favonius ontario (Northern Hairstreak), Parrhasius m-album (White-M Hairstreak), Satyrium calanus falacer (Banded Hairstreak), and Satyrium liparops strigosum (Striped Hairstreak) feed on the foliage, as do caterpillars of the skippers Erynnis brizo (Sleepy Duskywing) and Erynnis juvenalis (Juvenal's Duskywing). Probably several hundred species of moth caterpillars feed on the foliage and other parts of oaks. Moth caterpillars that feed on White Oak include Acronicta haesitata (Hesitant Dagger Moth), Catocala ilia (Ilia Underwing), Lambdina fervidaria (Curve-Lined Looper), Lymantria dispar (Gypsy Moth), Valentina glandulella (Acorn Moth), several Cameraria spp. (Blotch Leaf-Miners) and Phyllonorycter spp. (Tentiform Leaf-Miners), and other moths (see the Moth Table for a more complete listing of species). Other insects that feed on White Oak include the larvae of Acraspis erinacei (Hedge-Hog Gall Wasp) and other gall wasps, the larvae of Arrhenodes minutus (Oak Timberworm) and other wood-boring beetles (see Wood-Boring Beetle Table), the leaf beetles Cryptocephalus guttulatus and Lupraea picta, Stegophylla quercicola and other aphids, many species of treehoppers (see Treehopper Table), many species of leafhoppers (see Leafhopper Table), Asterolecanium variolosum (Golden Oak Scale), Corythucha arcuata (Oak Lace Bug), Lygocoris quercalbae (Oak Plant Bug) and other plant bugs, and Diapheromera femorata (Northern Walkingstick). Because the acorns of White Oak are produced annually and they are less bitter than those of the majority of oaks, they are an important source of food for many birds and mammals. Such birds as the Bobwhite, Ring-Necked Pheasant, Ruffed Grouse, Greater Prairie Chicken, Crow, and Blue Jay eat the acorns, as do such mammals as the Black Bear, Raccoon, Fox Squirrel, Gray Squirrel, Red Squirrel, Southern Flying Squirrel, Eastern Chipmunk, White-Footed Mouse, White-Tailed Deer, and wild hogs. White-Tailed Deer also browse on the twigs and foliage of White Oak, while the Cottontail Rabbit gnaws on the bark and twigs of saplings and seedlings during the winter (Haugen, 1942). Some birds construct nests on the branches of White Oak and other oaks, while other birds nest in the cavities of older trees. Tree squirrels, bats, and raccoons also use the cavities of older trees as dens.
Photographic Location: Crystal Lake Park in Urbana, Illinois.
Comments: White Oak is a very impressive tree at maturity with branches of exceptional length and size. It can be distinguished from other oaks (Quercus spp.) by its light gray bark with flat scaly ridges and shallow furrows, by its moderately to deeply lobed leaves, by the relatively even size of its lobes and their rounded tips, by the pale green and hairless undersides of its leaves, and by its medium-large acorns that have shallow warty cups without fringes. The highly regarded wood of White Oak is heavy, strong, flexible, and durable. It is used to make furniture, veneer, paneling, flooring, wooden barrels (including those that store whiskey and wine), caskets, railroad ties, fence posts, mine timbers, and wooden boats. It is also an excellent source of firewood.