Quercus douglasii Quercus douglasii
Quercus douglasii
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
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