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colorful fall leaves of rhus aromatica
Rhus aromatica ‘Gro-Lo’ (Fragrant Sumac) Photo © Mary Free
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Quercus phellos (Willow Oak)

Quercus phellos 2–3-inch long, drooping, yellowish male catkins with flowers consisting of a cup-shaped calyx and several stamens.
Quercus phellos male catkins in April.
Quercus phellos (willow oak) male catkins and new leaves in April.
The acorns of Quercus phellos (willow oak) take two years to mature after flowering. They usually occur singly or in pairs.
Quercus phellos (willow oak) acorns mature turning from green to brown between August and October.
Because Quercus phellos (willow oak) produces heavy mast most years, it is an important and dependable food source for wildlife.
The Alexandria Bicentennial Tree, a Quercus phellos (willow oak), which was 116 feet tall with a trunk circumference of 208 inches in November 2024, is believed to have sprouted around 1707.
Long-lived and fast-growing Quercus phellos (willow oak) in October in Arlington, Virginia.
Native Quercus phellos (willow oak) is a high-value wildlife tree. Its acorn ((¼-½" in size) production is also consistent but does not occur until trees are 15–20 years old.
The bark on the trunk of a Quercus phellos (willow oak) with gray squirrels in January.

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Quercus phellos Tried and True Native Plant Selections Willow Oak for the Mid-Atlantic Although bottomlands are its natural home, this handsome, long-lived native* tree thrives in cultivated landscapes. Alexandria’s Bicentennial Tree, a Willow Oak, dates back to about 1707. The National Park Service notes that Quercus supports more life forms than any other NA tree genus. Tree Summer & Fall Trees, Foliage, Catkins, Acorn Height: 40–90 feet Spread: 25–50 feet Bloom Color: Golden yellow to green Characteristics Moderately fast-growing, monoecious, deciduous tree with densely-branched, oval to rounded crown Alternate, simple, pinnate, lanceolate to linear, smooth-margined, bristle-tipped leaves, 1⁄4–1” wide by 2–5” long, shiny green above, paler below Yellowish, dangling, 2–3” male catkins; spike of 2–3 female flowers near stem tips March to April 1⁄2” round to ovoid acorn with shallow cupule topping striated brown nut, matures in 2nd year, Sep–Nov Fall foliage subtle golden to copper to brown Brown to gray bark, smooth with white lenticels when young, shallowly ridged and furrowed when mature; old trunks often fluted Attributes Tolerates salt, clay soil, occasional dry soil, flooding; can suffer wind damage, susceptible to acid rain Good resistance to usual oak pests and diseases; deer occasionally severely damage saplings Acorns edible if properly processed;** toxic to horses Provides hard mast, cover, nesting sites; larval host for ~513 lepidopterans, incl. numerous hairstreaks Growing and Maintenance Tips Excellent Replacement for Soil Requirements: Acidic, average, well-drained Acer platanoides - Norway Maple Light Requirements: Sun (preferred), Partial Shade Quercus acutissima - Sawtooth Oak Water Requirements: Moist, Wet Ulmus parviflora & U. pumila - Asian Elms Transplants well due to shallow, spreading roots *In the Mid-Atlantic, it is native to DC and common in the Coastal Plain of DE, MD, and VA (where it is also common in the Piedmont). It is present in PA’s Coastal Plain. **It is unsafe to eat raw acorns. Tannins must be leached out first. Remove caps and shells from mature, thoroughly dried acorns. Boil or soak nuts in water. Discard brown water and repeat process until water is clear and bitterness is gone. Reliable, ample nut crop most years on 20+ year trees Use as ornamental/shade (large) lawn or street tree Hardiness: USDA Zones 5a–9b developed by Master Gardeners of Northern Virginia, serving Arlington and Alexandria Images by Elaine Mills (top left, middle) and Mary Free (top right, bottom), street trees, Arlington County, VA

Tried and True Native Plant Selections 
for the Mid-Atlantic

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Quercus phellos (Willow Oak)

Although bottomlands are its natural home, this handsome, long-lived native* tree thrives in cultivated landscapes. The Alexandria Bicentennial Tree, a Willow Oak, dates back to about 1707. The National Park Service notes that Quercus supports more life forms than any other NA tree genus.

**In the Mid-Atlantic, it is native to DC and common in the Coastal Plain of DE, MD, and VA (where it is also common in the Piedmont). It is present in PA’s Coastal Plain. You can view the VA counties in which it has been reported here.

Learn more about other Mid-Atlantic plants: 
Tried and True Native Plant Fact Sheets