09/02/2021

Overcup Oak

The Ohio Chapter ISA continued efforts is to advance responsible tree care practices through research, technology, and education while promoting the benefits of trees. This month’s Tree-Of-The-Month is commonly known as the Overcup Oak.

The Overcup oak (Quercus lyrata) is also called swamp post oak, swamp white oak, and water white oak. The Overcup oak can grow 35-65 feet tall and wide. The Overcup oak is part of the White Oak group and is quite tolerant of flooding, grows slowly on poorly drained flood plains, and is often found in the swamps of the Southeastern United States. It is known that the Overcup oak may take up to 30 years before it produces acorns. Wildlife use these acorns as food. The Overcup oak often inhabits the wetter sites in bottomlands of the Coastal Plain from Delaware and Maryland, south to Georgia and northwestern Florida; west to eastern Texas. It grows northward in the Mississippi Valley to southeastern Oklahoma, southeastern Missouri, southern Illinois, southwestern Indiana, and western Kentucky. This tree is often found in cemeteries and arboretums in Ohio.  The Overcup oak derives its common name from the distinctive bur-like acorn cup that typically encloses two-thirds to almost all the nut. This distinctive bur-like acorn cup renders it buoyant in flood areas. Fall color of this tree’s species is variable from yellow or brown to red.

The national champion Overcup oak for 1976 was in South Carolina; it measured 22 feet in circumference, and was 123 feet (37 m) tall, and had a 48-foot (14.6-m) crown spread.  The largest Overcup oak (ranked by point system in 1990) was found in Texas and it was 51.1 inches (129.8 cm) in diameter, 160.53 inches in circumference, and 114 feet tall. Overcup oaks can live up to 400 years of age.

Planting Requirements

Overcup oak preforms well with soils that are poorly drained, alluvial, and clay soils. The Overcup oak-water hickory type is predominantly located on poorly drained backwater flats and small shallow sloughs commonly flooded for a few weeks after the growing season begins. Overcup oak is one of the trees most tolerant of flooding and is ideal for most new construction sites. Since it leaves out a month or more later than most tree species, it is better able to endure submergence from late spring floods. In tests, Overcup oak survived continuous flooding for at least two growing seasons. Despite its natural occurrence on wet clay sites, Overcup oak grows can thrive on sites with better drainage and soil texture like loams and silts. The Overcup oak can grow in a wide range of soil pH’s from > 6.0 to 8.0.

Property Maintenance and Public Safety

In pedestrian areas, fruiting clusters (Acorns) of Overcup oak must be cleaned up because they create human safety problems (for example, slip hazards by inadvertently stepping on a cluster or an individual acorns).

Check with a local Ohio International Society of Arboriculture Certified Arborist for what cultivars will work in your location.

Cultivars

Wide differences in quality of Overcup oak trees occur over its range. Generally, the better quality is found in its northern and eastern range. These differences, however, are probably due to response to site and seasonal flooding patterns rather than to genetic differences. Limited studies of juvenile variation within a small geographic area have not provided any evidence of genetic variation among localities. This tree species is often sold and are available from nurseries throughout the Ohio region, and it transplants easily in the spring of the year. Check with a local Ohio International Society of Arboriculture Certified Arborist for what type of plant will work in your location. Those types of transplants can be balled and burlap, container, and bare root plants.

Environmental Importance

Like many native insects and other biological components, most native oak trees is a high-value wildlife plant. Mildly deer resistant. Birds and small mammals eat the acorns. Oak trees support a wide variety of Lepidopteran. Those include Imperial Moth (Eacles imperialis) larvae, Banded Hairstreak (Satyrium calanus), Edward's Hairstreak (Satyrium edwardsii), Gray Hairstreak (Strymon melinus), White-M Hairstreak (Parrhasius m-album), Horace’s Duskywing (Erynnis horatius), and others.

Ethnobotany

The Overcup oak wood is used for lumber and cooperage, and it is low quality when compared to the wood of other white oaks. Acorns of most oak species have been used as food by humans. The bark of oak trees has been used to make dyes, and for tannin extraction.

Tree Selection Tips

The Ohio Chapter ISA recommends working with an ISA Certified Arborist when selecting or caring for any tree in your landscape. To better guide you on the vital plant information for Overcup oak, use our friendly users guide below:

Written by Mark A. Webber BCMA, CPH, LTE,  MArborA, OCMNT, TRAQ, TPAQ

Sources:

https://www.srs.fs.usda.gov/pubs/misc/ag_654/volume_2/quercus/lyrata.htm (Collected on August 28, 2021

https://plants.ces.ncsu.edu/plants/quercus-lyrata/ (Collected on August 28, 2021)

https://www.fs.fed.us/database/feis/plants/tree/quelyr/all.html#:~:text=WOOD%20PRODUCTS%20VALUE%20%3A%20Overcup%20oak,overcup%20oak%20acorns%20%5B18%5D. (Collected on August 28, 2021)

U.S. Department of Agriculture, Forest Service. 1965. Silvics of forest trees of the United States. H. A. Fowells, comp. U.S. Department of Agriculture, Agriculture Handbook 271. Washington, DC. 762 p

Photograph sources Ronald Rothus 2020

Photograph sources MkWebber 2021