Alameda County Thistle

Cirsium quercetorum

Native to:
United States

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Taxonomy

Division:
Magnoliophyta | - Flowering plants
Family:
Asteraceae
Genus:
Cirsium
Species:
Cirsium quercetorum
USDA Symbol:
CIQU2

Growth Characteristics

Life Cycle:
Biennial | Perennial
Growth Habit:
Forb/herb
Height:
60 cm
Light Requirements:
Full Sun
Drought Tolerance:
Medium
Bloom Months:
apr,may,jun,jul
Bloom Colors:
pink, purple, lavender

Wildlife Benefits

Bees:
★☆☆☆☆ Documented bee visitation (GBIF)
Butterflies & Moths:
★☆☆☆☆ Documented Lepidoptera association (GBIF)

Keystone Species Ranking

Pollen Specialist Bee Keystone:
★★★★☆ Native pollen specialist bee species supported by this genus (NWF)

Garden & Ecology Notes

Wildlife Value:
bees, butterflies, birds
Deer Resistant:
Yes
Fire Ecology:
Fire adapted — tolerates or benefits from fire
Fire Notes:
Resprouts from root crown after fire. Native to fire-prone oak woodland and chaparral ecotones.

Soil Requirements

Soil Type:
well-drained, sandy or rocky soil
pH:
6.0 - 7.5 (slightly acidic to neutral)
Drainage:
excellent drainage required
Moisture:
dry to moderate
Notes:
native to open, dry habitats; prefers full sun

Propagation & Germination

Stratification:
Cold/moist stratification required — 30–60 days
Germination Time:
14–28 days
Notes:
Seeds germinate readily after cold stratification. Light may enhance germination.

The above propagation data sourced from Claude AI