Blue Oak
Quercus douglasii
- Native to:
- United States
Eugene Zelenko
Taxonomy
- Division:
- Magnoliophyta | - Flowering plants
- Family:
- Fagaceae
- Genus:
- Quercus
- Species:
- Quercus douglasii
- USDA Symbol:
- QUDO
Growth Characteristics
- Life Cycle:
- Perennial
- Growth Habit:
- Tree
- Height:
- 1500 cm
- Light Requirements:
- Full Sun
- Drought Tolerance:
- High
- Bloom Months:
- mar,apr,may
Wildlife Benefits
- Butterflies & Moths:
- ★☆☆☆☆ Documented Lepidoptera association (GBIF)
- Caterpillars:
- ★★★☆☆ Recorded caterpillar host plant (HOSTS Database)
Keystone Species Ranking
- Caterpillar Keystone:
- ★★★★★ Butterfly & moth species supported by this genus (NWF)
Host Plant for Caterpillars
Acrobasis comptella, Aristotelia urbaurea, California oakworm (Phryganidia californica), Caloptilia sp., Cameraria lobatiella, Cameraria pentekes, Cameraria serpentinensis, Cameraria temblorensis, Chionodes formosella, Chionodes occidentella, Chionodes raspyon, Chionodes trichostola, Coleophora querciella, Decodes fragariana, Dyseriocrania auricyanea, Epinotia emarginana, Evippe laudatella, Feralia februalis, fruit-tree leafroller (Archips argyrospila), Pacific tent caterpillar (Malacosoma constricta), Rhodophaea fria, Telphusa sedulitella, Xenolechia querciphaga, Gold-hunter's hairstreak (Satyrium auretorum), Mournful Duskywing (Erynnis tristis)
Reported Fauna Sightings
Bees: ⚠️Western honey bee (Apis mellifera) Hummingbirds: Anna's Hummingbird (Calypte anna) Moths:Copper Underwing (Amphipyra pyramidoides), marbled dagger moth (Acronicta marmorata), Pacific tent caterpillar (Malacosoma constricta) Butterflies:California Sister (Adelpha californica)
Garden & Ecology Notes
- Wildlife Value:
- birds, small mammals, deer
- Fall Color:
- yellow, orange
- Fire Ecology:
- Fire adapted — tolerates or benefits from fire
- Fire Notes:
- Resprouts vigorously from root crown after fire; thick bark provides moderate protection in mature trees. Historically maintained by low-intensity ground fires.
Soil Requirements
- Soil Type:
- rocky, well-drained, nutrient-poor soil
- pH:
- 5.5 - 7.5 (slightly acidic to neutral)
- Drainage:
- excellent drainage required
- Moisture:
- dry to moderate
- Notes:
- Thrives in foothill regions with minimal water availability.
Propagation & Germination
- Stratification:
- Cold/moist stratification required — 30–60 days
- Germination Time:
- 14–60 days
- Notes:
- Acorns have low dormancy; fresh acorns may germinate without stratification but cold treatment improves uniformity.
The above propagation data sourced from Claude AI
Pre-treatment: None required
Establishment: Q. douglasii is found on dry rocky slopes from Los Angeles county north to the Sacramento valley, California.
Source: npn.rngr.net