Shingle Oak is monoecious, producing separate male (staminate) and female (pistillate) flowers on the same tree. Male flowers are produced in drooping yellowish catkins about 3" long. Each male flower is less than 1/8" (3 mm.) across, consisting of an irregularly lobed calyx and several stamens. Female flowers occur near the tips of twigs as the vernal leaves unfold; either short clusters of 2-4 female flowers or individual female flowers are produced. Each female flower is less than ¼" long, greenish red, and ovoid in shape, consisting of an ovary, a calyx that surrounds the ovary, and 3 stigmata at the apex. Underneath each female flower, there are scale-like bractlets with downy hairs. The blooming period occurs during mid- to late spring for about 2 weeks; the flowers are cross-pollinated by wind. Afterwards, fertile female flowers are replaced by acorns that take 2 years to develop; they become mature during the autumn of the second year. Acorns usually occur along the twigs either individually or in clusters of 2; they have short woody pedicels. Mature acorns are about 10-15 mm. long and a little less across, consisting of a light brown cup and a brown nut. Each cup extends about one-third the length of an acorn. The meat of the acorn is bitter. The root system consists of a taproot with spreading lateral roots.
Cultivation: This tree prefers full or partial sun and moist to dry conditions; it adapts to many soil types, including those that contain loam, clay-loam, sand, and some rocky material. Good drainage is required. To a greater extent than other oak trees (Quercus spp.), the appearance of Shingle Oak is often marred by gall-making insects.
Range & Habitat: The native Shingle Oak is common in all areas of Illinois, except the NW section of the state, where it is largely absent (see Distribution Map). Illinois lies along the NW range-limit of this tree. Habitats consist of upland woodlands, well-drained areas of floodplain woodlands, wooded slopes and edges of bluffs, tall riverbanks, edges of limestone glades, sandstone cliffs, and fence rows. In addition to these habitats, Shingle Oak is occasionally cultivated as a landscape tree.
Faunal Associations: Various insects feed on Shingle Oak and other oaks; these insects feed on the foliage, suck plant juices, consume the meat of acorns, and bore through the wood or roots. The following leafhoppers prefer Shingle Oak as a host plant: Eratoneura alicia, Eratoneura amethica, Eratoneura arpegia, Eratoneura confirmata, Eratoneura econa, Eratoneura imbricariae, Eratoneura metopia, and Eratoneura trivittata (see Dmitriev & Dietrich, 2010). Other insects that have been observed to feed on Shingle Oak include the leaf-mining larvae of the moths Coptotriche castaneaeella, Coptotriche citrinipennella, and Phyllonorycter basistrigella. More generally, other insects that feed on oaks (Quercus spp.) include the caterpillars of some Hairstreak butterflies and Duskywing skippers, the caterpillars of other moths, aphids, treehoppers, plant bugs, lace bugs, leaf beetles and their larvae, the larvae of weevils, the larvae of wood-boring beetles, the larvae of gall wasps, the larvae of sawflies, grasshoppers, and walkingsticks. The Moth Table, Wood-Boring Beetle Table, and Insect Table list these species more specifically. The acorns of oaks are eaten by many birds and mammals. Such birds as the Wild Turkey, Bobwhite, Blue Jay, White-Breasted Nuthatch, Tufted Titmouse, and others eat acorns. Among mammals, the Black Bear, Opossum, Raccoon, Southern Flying Squirrel, Gray Squirrel, Fox Squirrel, Red Squirrel, Eastern Chipmunk, White-Footed Mouse, and White-Tailed Deer eat acorns. White-Tailed Deer also browse on the twigs and foliage. Cavities in older oak trees provide dens for many mammals and cavity-nesting birds; other birds build nests along the leafy branches. Such insectivorous birds as warblers, thrushes, vireos, and flycatchers are often found in oaks because of the large number of insects and other invertebrates that these trees attract. In general, the value of Shingle Oak and other oaks to wildlife is quite high.
Photographic Location: An upland area of Busey Woods in Urbana, Illinois.
Comments: Shingle Oak is one of two oaks (Quercus spp.) in Illinois that has leaves with smooth margins; other oaks have pinnatifid leaves. The other oak species with smooth-margined leaves, Quercus phellos (Willow Oak), is found in southern Illinois. The leaves of Willow Oak are more narrow (½" or less) than those of Shingle Oak. At one time, the wood of Shingle Oak was used to make wooden shingles for houses, hence the common name. Other common names for this tree are Jack Oak and Northern Laurel Oak.