blue oak (Quercus douglasii)

Native: Central and Southern California

General Notes:

• A slow growing native oak. Commonly found on interior California hills.
• A Quercus douglasii in Mariposa is registered as a California Big Tree. It measures 71 feet high, with a trunk circumference of 146 inches and a crown spread of 79 feet.

Tree Characteristics

• Shape: Oval, Rounded or Umbrella
• Foliage: Deciduous, Oblong to Ovate, Blue Green, Bronze, Gold, Orange or Multicolored
• Height: 50 - 65 feet.
• Width: 40 - 50 feet.
• Flowers: Inconspicuous. Flowers in spring.
• Fruit: Prolific, Brown Acorn, Medium (0.50 - 1.50 inches), fruiting in fall or winter.
• Bark: Light Gray, Furrowed, Scaly or Smooth.
• Shading Capacity: Moderate in Leaf, Moderate out of Leaf.
• Litter Issue: Dry Fruit

Tree Site Conditions & Constraints

• Zones: Sunset 3 - 11 and 14 – 24, USDA Hardiness 6 - 9
• Exposure: Full Sun to Partial Shade

Pests & Disease Information

• Resistant: Verticillium.
• Susceptible: Caterpillars, Insect Galls, California Oak Moth, Gall Wasp and Scales, Crown Rot, Mistletoe, Oak Root Rot, Brown Rot, Powdery Mildew and Root Rot.

Health, Safety & Environmental Concerns

• Branch Strength: Strong
• Root Damage Potential: Low
• Health Hazard: Allergy and Poisonous
• Biogenic Emissions: Moderate
• Attracts: Birds and Squirrels

Source:

SelecTree. "Quercus douglasii Tree Record." 1995-2018. Feb 22, 2018. < https://selectree.calpoly.edu/tree-detail/quercus-douglasii >