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Reveal, James L.

Quercus douglasii

Quercus douglasii Hook. & Arn.

Blue Oak

Fagaceae (Beech Family)

Synonym(s):

USDA Symbol: QUDO

USDA Native Status: L48 (N)

Tree with short, leaning trunk; short, stout branches; broad, rounded crown; and brittle, hairy twigs; sometimes shrubby. Blue oak is a deciduous oak, usually growing to 30 ft., but sometimes reaching 50 ft. The crown is rounded. Bluish-green leaves are shallowly lobed, without bristles. Bark is light-colored and checked into thin scales.

Recognized from a distance by the bluish foliage, this handsome California oak was named for its discoverer, David Douglas (1798-1834), the Scottish botanical explorer. It is used principally for fuel. The acorns, often abundant, are eaten by livestock as well as by wildlife.

From the Image Gallery

14 photo(s) available in the Image Gallery

Plant Characteristics

Duration: Perennial
Habit: Tree
Leaf Retention: Deciduous
Leaf Arrangement: Alternate
Leaf Complexity: Simple
Leaf Venation: Pinnate
Breeding System: Flowers Unisexual , Monoecious
Inflorescence: Catkin
Fruit Type: Nut
Size Notes: Up to about 50 feet tall.
Leaf: Gray-Green

Bloom Information

Bloom Color: Yellow
Bloom Time: Mar , Apr , May

Distribution

USA: CA
Native Distribution: Throughout CA, mostly in foothills of Coast Ranges & Sierra Nevada
Native Habitat: Dry, rocky slopes below 3500 ft.

Growing Conditions

Water Use: Low
Light Requirement: Sun
Soil Moisture: Dry
CaCO3 Tolerance: None
Soil Description: Dry, rocky soils.
Conditions Comments: Slow-growing. Drought-tolerant.

Propagation

Description: Oaks are most often propagated from seed. No pretreatment is necessary. Plant immediately – outdoors or in deep containers to accomodate long initial taproot. Many oaks require cold temperatures to initiate shoot development. Protect outdoor beds with
Seed Collection: Best quality acorns are picked or shaken from the tree. Collect when color has changed to brown. Best if sown immediately as acorns lose viability quickly in storage. Short-term storage in moist, shaded saw dust or sand. Acorns to be sown immediately can be soaked in hot water for 15 min. to prevent weevil infestation. Stored seed should be fumigated with methyl bromide.
Commercially Avail: yes

Find Seed or Plants

Find seed sources for this species at the Native Seed Network.

View propagation protocol from Native Plants Network.

From the National Organizations Directory

According to the species list provided by Affiliate Organizations, this plant is on display at the following locations:

Santa Barbara Botanic Garden - Santa Barbara, CA
Native Seed Network - Corvallis, OR

Bibliography

Bibref 841 - Native Alternatives to Invasive Plants (2006) Burrell, C. C.

Search More Titles in Bibliography

Web Reference

Webref 3 - Flora of North America (2014) Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.

Additional resources

USDA: Find Quercus douglasii in USDA Plants
FNA: Find Quercus douglasii in the Flora of North America (if available)
Google: Search Google for Quercus douglasii

Metadata

Record Modified: 2022-09-23
Research By: TWC Staff

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