| Common Name |
Blue Oak |
| Latin Name |
Quercus douglasii |
| Family |
Fagaceae |
| Sunset zones / USDA zones |
3-11, 14-24 / 5-10 |
| Type / Form |
Tree / Large |
| Native Habitat |
Interior California from 300 to 4,500 feet |
| Soil |
Dry decomposed granite, sand, limestone, clay loam, low organic content, well drained |
| Water |
Once per month |
| Exposure |
Full sun |
| Height X Width |
Maximum 30 feet X 30 feet, usual 25 feet X 25 feet |
| Protective Mechanism |
None |
| Leaves |
Alternate, simple, and usually deciduous
(although trees on moist sites may retain their leaves); 1 to 3 inches
long; margins are usually wavy, but are sometimes shallowly and
irregularly lobed; the upper side of the leaf is distinctly
bluish-green, especially later in the growing season, while the lower
surface is pale green. |
| Flowers |
Monoecious; males are borne in pendent yellow-green
catkins (aments); females are small, often solitary, and occur in the
axils of leaves on current year's twigs; appearing in spring.
Acorns;
oval to gently tapering; 3/4 to 1 1/2 inches long; shallow caps with
warty scales; ripen in a single year. |
| Bark / Roots |
Mature bark is light gray and checkered.
Twigs stout,
brittle, and gray to reddish brown. |
| Maintenance |
Low |
| Propagation |
Seeds |
| Pests and diseases |
Resistant to Verticillium. Susceptible to Aphids, Beetle
Borers, Beetle Grubs, Caterpillars, Coddling Moths, Insect Galls, Scales
and White Fly, Sudden Oak Death, Crown Rot, Mistletoe, Oak Root Rot,
Phytophthora, Powdery Mildew, Root Rot and Sooty Mold. |
| Landscape uses |
Erosion control, windbreak, borders, low maintenance,
fire retardant |
| Garden Suitability |
Songbird, Mountain, Butterfly, Thornless |
| Nature Value |
Large acorns eaten by squirrels and strong beaked birds, cover
for nesting birds, larval plant for butterflies and other insects |
| Native American Uses |
Acorns ground to make soup and flour for unleavened
bread, bark used for black dye |
| Links |
|
| Images, and
data |
http://bss.sfsu.edu/holzman/courses/Fall99Projects/blueoak.htm |
| Images, and
data |
http://www.na.fs.fed.us/pubs/silvics_manual/volume_2/quercus/douglasii.htm |
| Images, and
data |
http://www.blueplanetbiomes.org/blue_oak.htm |
| Images, and
data |
http://www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=6990 |
| Images, and
data |
http://www.pfaf.org/database/plants.php?Quercus+douglasii |
| Images and data |
http://www.cnr.vt.edu/dendro/dendrology/syllabus/factsheet.cfm?ID=314 |
| Images and data |
http://www.fs.fed.us/database/feis/plants/tree/quedou/all.html |
| Images and data |
http://www.desert-tropicals.com/Plants/Fagaceae/Quercus_douglasii.html |
| Images and data |
http://trees.stanford.edu/ENCYC/QUEdou.htm |
| Images and data |
http://en.wikipedia.org/wiki/Quercus_douglasii |
| Images and data |
http://www.theodorepayne.org/mediawiki/index.php?title=Quercus_douglasii |
| Images |
http://www.baynatives.com/plants/Quercus-douglasii/ |
| Image |
http://www.forestryimages.org/browse/detail.cfm?imgnum=1312023 |
| Images |
http://www.coestatepark.com/quercus_douglasii.htm |
| Data |
http://www.gardenguides.com/taxonomy/blue-oak-quercus-douglasii/ |
| Data |
http://www.wildflower.org/plants/result.php?id_plant=QUDO |
| Nursery, images, and data |
http://www.laspilitas.com/plants/555.htm |
| Nursery, images, and data |
http://www.cnplx.info/nplx/species?taxon=Quercus+douglasii |
| Nursery |
Oak Hills Nursery, 13874 Ranchero Road, Oak Hills, 92345,
760-947-6261 |
| Distribution map |
http://plants.usda.gov/java/profile?symbol=QUDO |
| Distribution map |
http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233501022 |
| Note: |
Moderate pollinator |
