Overcup oak (Quercus lyrata): what the agencies record

This page reports what US federal publications say about one tree. It does not identify trees from descriptions or photos and does not say what should be done with any tree. The family overview, tree species in the agency records, explains the sources and holds the comparison table.

At a glance

Item	What the source records
Scientific name	Quercus lyrata Walter in USDA PLANTS, beech family
Other names	Swamp post oak, swamp white oak and water white oak (Silvics)
Native status, USDA PLANTS	Native in the lower 48 states
Size and age, Silvics	A medium-size tree 18 to 27 m (60 to 90 ft) tall and 61 to 76 cm (24 to 30 in) in diameter; height rarely exceeds 30 m (100 ft), diameters over 91 cm (36 in) are uncommon, and the maximum age is about 400 years
Form, Silvics	A short trunk that is frequently crooked or spiraled, with a broad, wide-spreading, open crown
Roots, Silvics	A shallow, saucer-shaped root system; seedlings start with taproots that are replaced by a lateral system
Green weight of the wood, NRS-38	63 lb per cubic foot, without bark

Native range and sites

The Silvics of North America handbook (Agriculture Handbook 654, volume 2, 1990) says overcup oak inhabits the wetter sites in bottom lands of the Coastal Plain from Delaware and Maryland south to Georgia and northwestern Florida and west to eastern Texas, and grows northward in the Mississippi Valley to southeastern Oklahoma, southeastern Missouri, southern Illinois, southwestern Indiana and western Kentucky. It calls the species quite tolerant of flooding and says it grows slowly on poorly drained flood plains and swamp lands, taking as long as 30 years before it produces acorns.

Flowers and fruit

Silvics says overcup oak is monoecious, with male flowers in naked catkins and female flowers in spikes. Flowers appear while the leaves develop, in April and May in the Mississippi Delta. The acorn is 12 to 25 mm (0.5 to 1 in) long, flattened and spherical, and may be entirely covered by a scaly cup, which is the source of the common name. Acorns mature within one growing season, ripen by September or October and fall soon after.

Growth and lumber quality

On the best sites the handbook says overcup oak may add 10 cm (4 in) of diameter over a 10-year span, while old trees on low flats subject to backwater overflow may add only 5 cm (2 in) over a 50-year span. It describes the quality of the wood as varying greatly across the range but generally medium to poor, because of insects, shake and other factors, and says the species yields about half as much top-grade lumber as other white oaks. It quotes an older source calling overcup oak the "poorest of the white oaks" after post oak, and says overflow-site wood from the Mississippi Delta was difficult to dry without serious checking and honeycombing. Quality is poorest in the southern half of the Delta and fair to very good north of a line the handbook places from Eudora, Arkansas, to Greenwood, Mississippi.

Wood

Silvics says the wood is cut and sold as white oak, that logs from the best sites may be used for lumber and sometimes tight cooperage, but that the wood is frequently worthless for factory lumber and other quality products, and checking during seasoning often prevents general use even as ties and timbers. The Wood Handbook (FPL-GTR-282, 2021) lists overcup oak among the principal species of the white oak group; that group is described on the white oak page. Table 5-3b has a separate overcup oak row, shown below.

Wood Handbook Table 5-3b	Specific gravity	Modulus of rupture (lbf per square inch)	Side hardness (lbf)
Green	0.57	8,000	960
At 12% moisture content	0.63	12,600	1,190

The Wood Handbook states that specific gravity is based on oven-dry weight and the volume when green or at 12% moisture content. The green weight of the wood without bark is in the NRS-38 table, the same figure used in the log weight calculator.

Diseases, insects and damage the handbook names

Silvics (1990) says overcup oak has a name for many defects, which it traces mostly to wood borers and to heartwood that decays quickly after fire injury.

Trunk borers. The carpenterworm (Prionoxystus robiniae) and the red oak borer (Enaphalodes rufulus) are named as the two most damaging large trunk borers of sawtimber, making galleries 12 to 18 mm (0.5 to 0.7 in) across and 15 to 25 cm (6 to 10 in) long. The white oak borer (Goes tigrinus) is damaging to young trees up to about 20 cm (8 in) in diameter.
Grease spot. On sites flooded by backwater from December through June, a borer (Agrilus acutipennis) leaves a small frass-packed hole surrounded by a dark-stained area, which the handbook says degrades lumber and ruins the wood for tight cooperage.
Bark pockets. Pockets of ingrown bark and stained wood left where borers, particularly the red oak borer and carpenterworm, attacked the bark and cambium and then healed over.
Defoliators. Usually not very harmful; the handbook cites a 1952 outbreak of the basswood leafminer (Baliosus ruber) that severely weakened trees and reduced growth.
Heart rots. Heart rots of the Poria, Polyporus and Hericium groups follow injuries, especially fire injuries; the handbook says other diseases are not serious. See flooding injury to trees for the flooding side.

The guide on reporting a pest in the United States and the Canada reporting page give the offices that take sightings of regulated pests. Who may apply pesticides is in pesticide licences by country.