Photo: Katherine Wagner-Reiss, CC BY-SA 4.0 · Wikimedia Commons
Overcup Oak
Quercus lyrata
Also called swamp post oak, water white oak.
A bottomland white oak that stands in floodwater for months and then takes a dry summer in stride, with acorns almost swallowed by their cups.
Tolerates wet soilWildlife value
- Type
- Large tree
- Mature height
- 40–60 ft
- USDA zones
- 5–9
- Growth rate
- Medium
- Sun
- Full
- Soil moisture
- Average · Wet
210
Overcup oak is the white oak of the wettest ground in the South: backwater flats, sloughs and river bottoms from the Delmarva Peninsula south to Florida, west to Texas and up the Mississippi valley to southern Illinois and Indiana, on sites flooded well into the growing season. The cup wraps nearly the whole acorn, which is why the nut floats and why the tree spreads along water, and unlike most white oaks its acorns wait until spring to germinate. The leaves are lyre-shaped with a whitish underside, the bark grey and scaly like white oak, and the wood is sold as white oak. Perfect for a wet lawn corner, a floodplain planting or a parking strip that floods in spring and bakes in summer.
What has made it a favorite of city foresters is that the same tree that tolerates standing water also takes compacted clay and drought once established, and grows into a tidy, upright crown of 40 to 60 feet without the wide limbs of a white oak. Mallards and wood ducks take the floating acorns, along with deer, squirrels and turkeys.
How to grow Overcup Oak
Overcup oak wants full sun and is hardy in zones 5 through 9. It is at home in soil that floods or stays wet for weeks, including heavy clay, and once established it also tolerates an ordinary lawn and summer drought. It grows 40 to 60 feet tall with a crown about two thirds as wide, so give it 25 feet from a house and keep it clear of overhead wires.
Plant bare-root saplings while dormant, from late fall until buds swell, in a hole twice the width of the roots and no deeper, root flare at grade, backfilled with the soil that came out. Mulch a ring three inches deep, kept off the trunk, and skip the stake unless the site is windy. Acorns are unusual for a white oak in that they do not sprout in fall: store them cold and moist over winter and sow them in spring an inch deep, or sow in fall under hardware cloth and expect germination in April or May.
Water deeply once a week through the first summer and in dry spells for two more; a tree from a flooded bottom still needs water while its roots are small. Deer browse and rub young oaks, so keep a tube or cage on for three or four years. Prune only to a single leader and to remove crossing limbs, in late winter.
Growth is moderate, faster on deep moist soil than on a dry bank. Acorns begin after 25 years or so, in good crops every three or four years.
Heights and zones are typical ranges for the species in cultivation; local conditions and seed source shift them.
More like this
