Douglas' Thistle

Cirsium douglasii

Native to:
United States

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Taxonomy

Division:
Magnoliophyta | - Flowering plants
Family:
Asteraceae
Genus:
Cirsium
Species:
Cirsium douglasii
USDA Symbol:
CIDO2

Growth Characteristics

Life Cycle:
Biennial | Perennial
Growth Habit:
Forb/herb
Height:
200 cm
Light Requirements:
Full Sun
Drought Tolerance:
Low
Bloom Months:
jun,jul,aug,sep
Bloom Colors:
purple, pink

Wildlife Benefits

Bees:
★☆☆☆☆ Documented bee visitation (GBIF)
Butterflies & Moths:
★☆☆☆☆ Documented Lepidoptera association (GBIF)
Caterpillars:
★☆☆☆☆ Recorded caterpillar host plant (HOSTS Database)

Keystone Species Ranking

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

Host Plant for Caterpillars

Mylitta crescent (Phyciodes mylitta)

Reported Fauna Sightings

Bees: Two-form bumble bee (Bombus bifarius), Yellow-faced bumble bee (Bombus vosnesenskii)

Garden & Ecology Notes

Wildlife Value:
bees, butterflies, birds

Soil Requirements

Soil Type:
moist, rich, well-drained loamy soil
pH:
5.5 - 7.5 (slightly acidic to neutral)
Drainage:
tolerates poor drainage
Moisture:
consistently moist
Notes:
commonly found in wetlands and marshy areas

Propagation & Germination

Stratification:
Cold/moist stratification required — 30–60 days
Germination Time:
14–30 days
Notes:
Seeds benefit from cold moist stratification for 4-8 weeks to break dormancy.

Pre-treatment: Cold-moist stratification for 30 days at 1–5°C (34–41°F).

Source: Claude AI