Quercus douglasii

Blue oak

Family: Fagaceae · Type: tree · Native

Blue oak is a California native tree found in the Klamath Ranges, northern Coast Ranges, California Robles, Sierra Nevada Foothills, Tehachapi, Sutter Buttes, San Joaquin Valley, San Francisco Bay Area, southern Coast Ranges, southern Channel Islands, and Mojave Desert in dry woodland slopes and interior foothills at elevations below 1,590 meters. Flowering from April to May, this tree produces pale greenish-yellow flowers in small clusters. Growing 6 to 20 meters tall with a distinctive checkered gray bark that breaks into thin scales, it develops a broad, spreading canopy. Its leaves are 3 to 6 centimeters long, oblong to obovate with a blue-green color, featuring a rounded tip and slightly wavy margins. The acorns mature within one year, with cups 12 to 20 millimeters wide and nuts 20 to 35 millimeters long, developing an ovoid shape with a subtly acute tip.

Habitat: dry slopes, interior foothills, woodland

Bloom period: Apr-May

Elevation: < 1590 m

Bioregions: KR, NCoRO, NCoRI, CaRF, SNF, Teh, ScV (Sutter Buttes), SnJV, SnFrB, SCoR, s ChI (Santa Catalina Island), WTR (n slope), MP.

California counties: San Luis Obispo, Kern, Amador, Napa, Monterey, Madera, Yuba, Shasta, Lake, Sacramento, Santa Barbara, San Benito, Tehama, Contra Costa, Butte, Santa Clara, Sutter, Mariposa, Fresno, Tuolumne, San Mateo, Los Angeles, Tulare, Yolo, San Joaquin, Mendocino, Placer, Calaveras, Nevada, Sonoma, El Dorado, Marin, Sierra, Inyo, Colusa, Glenn, Kings, Alameda, Stanislaus, Solano, Merced, Ventura, Trinity, Riverside, Siskiyou, Del Norte

Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Jepson eFlora, Cal-IPC, and more.