White oak (Quercus alba) is a member of the broad white oak group (white, bur, chinkapin, swamp white, and post oaks). This group is characterized by having rounded lobes on the leaves and acorns which mature in a single growing season and sprout soon after they fall in the autumn.
Habitat: Grows on upland woods and dry slopes. Common in most of the state except northwest Iowa.
Hardiness: Varies with the species of oak tree, ranging from zone 3 to zone 9
Growth Rate: Slow to Moderate
Mature Shape: Broad, rounded
Height: Varies with species. Often maturing between 50 to 75 feet tall. Capable of growing upwards of 100 feet.
Width: 40 to 70 feet. Varies with species
Site Requirements: Best growth in moist, well-drained soils. Adaptable to adverse soil conditions.
Leaves: Alternate, simple, lobed; with rounded tips.
Flowering Dates: May
Seed Dispersal Dates: October
Seed Bearing Age: 20 years
Seed Bearing Frequency: Every 4 to 10 years
Seed Stratification: No stratification period is needed.
White oak leaves are simple and arranged alternately on twigs. They are 7 to 9 lobed, 5 to 9 inches long with short petioles. The lobes are rounded without bristle tips and vary in length from leaf to leaf but are rather uniform on the same leaf. Surface color is dull green and paler below. Twigs are moderately stout, red often with a purplish tinge. Buds are clustered at the tips, blunt to oval in shape and usually reddish brown to brown in color. The bark on mature trees is light ashy gray in color, separating into small scaly plates; on old trees, bark may be furrowed with rectangular blocks.
White oak is native to most of Iowa except far western Iowa and the Northwestern corner of the state. In its range, white oak is one of the most abundant trees, often dominating the drier upland forested areas. It also occurs on moist sites, but usually is found in greater abundance towards the ridges and drier sites. It prefers soils which are moderately well drained or better and slightly acidic.
Its common associates are other oaks, hickories, ironwood, black cherry, white ash, aspens on drier sites and maple, basswood, and bitternut hickory on more moist sites. White oak is moderately intolerant to shade. As a result, most successful oak seedlings are usually found areas which receive full sunlight during part of the day.
White oak grows slow (approximately 1 foot per year) and has a long live span (350-500 years). It commonly attains a height of 80 to 100 feet with a diameter of 3 to 4 feet. Fall color is wine color eventually fading to brown. The leaves of white oak often persist through mid winter adding to the attractiveness of this tree.
White oak is not used extensively for landscaping in Iowa because of its slow growth rate and difficulty of transplanting this species. It should be used more and success in establishment will be increased by using relatively small material.
The strength, hardness, durability, and widespread availability of white oak have made its wood one of the most important hardwoods in the US and Iowa. Its uses include railroad ties and timbers, flooring, furniture and paneling. Its density has also make it one of the most popular fire woods.