English oak (Quercus robur)

First place champion (tied) English oak in Denver.

Species info:

Leaves: Alternate, simple, 2–5 inches long and ¾–2½ inches wide with 6–14 shallow, rounded lobes.

Leaf Surface: Thick, leathery, and glossy; dark green to blue-green above and pale blue-green below.

Bark: Smooth and gray-brown when young, becoming dark gray, rough, and deeply furrowed with age.

Flowers: Male flowers appear as yellow-green catkins in spring; female flowers are small and inconspicuous.

Fruit: Acorns ½ inch wide and 1 inch long, shiny brown, usually enclosed one-third by a cap. Occur singly or in clusters of up to five. Mature in one season (a characteristic of white oaks).

Botanical: Quercus gambelii

Family: Fagaceae

Mature Height: 60–100 feet

Canopy Spread: 40–80 feet

Foliage Type: Deciduous

Tree Shape: Round

Growth Rate: Moderate

Flower: Inconspicuous

Fruit: Edible acorn, but requires processing

Fall Color: Yellow to brown; often persists into winter

Water Use: Moderate; drought tolerant once established but less xeric than Bur or Gambel oak

Hardiness: Zones 4–8

Soil Preference: Adapts well to most soil types; performs best in deep, fertile, well-drained soils

Sun Exposure: Full sun

Wildlife Value: Acorns provide food for birds, squirrels, and deer; dense canopy offers shade and shelter

Pests/Pathogens: Gambel oak borer; may occasionally experience powdery mildew or oak leaf blister

Planting Recommendations: Recommended for most sites, but there is growing concern for susceptibility to Gambel oak borer

Varieties: Quercus robur ‘Fastigiata’ - Height to 45 feet with a spread of up to 15 feet; strongly upright and columnar shaped tree that will spread as the tree matures and lateral branches get larger.

Information Sources:

• Front Range Tree Recommendation List

• Michael Dirr, Manual of Woody Landscape Plants (University of Georgia, 1990)