Elk Thistle
Cirsium foliosum
- Native to:
- Canada, United States
iNaturalist: © johanna_s (iNaturalist #329260161)






Taxonomy
- Division:
- Magnoliophyta | - Flowering plants
- Family:
- Asteraceae
- Genus:
- Cirsium
- Species:
- Cirsium foliosum
- USDA Symbol:
- CIFO
Growth Characteristics
- Life Cycle:
- Perennial
- Growth Habit:
- Forb/herb
- Height:
- 120 cm
- Light Requirements:
- Full Sun
- Drought Tolerance:
- Medium
- Bloom Months:
- jun,jul,aug,sep
- Bloom Colors:
- white, pink, purple
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)
Reported Fauna Sightings
Bees: White-shouldered bumble (Bombus appositus), Yellow-faced bumble bee (Bombus vosnesenskii)
Garden & Ecology Notes
- Wildlife Value:
- bees, butterflies, birds
- Deer Resistant:
- Yes
- Fire Ecology:
- Fire adapted — tolerates or benefits from fire
- Fire Notes:
- Resprouts from rootstock following fire. Common in post-fire meadow and montane communities.
Soil Requirements
- Soil Type:
- moist, well-drained loamy soil
- pH:
- 5.5 - 7.0 (slightly acidic to neutral)
- Drainage:
- good drainage required
- Moisture:
- consistently moist
- Notes:
- prefers nutrient-rich soils in native habitats
Propagation & Germination
- Stratification:
- Cold/moist stratification required — 30–60 days
- Germination Time:
- 14–30 days
- Notes:
- Cold stratification improves germination rates. Seeds may germinate without stratification but at lower rates.
The above propagation data sourced from Claude AI
Pre-treatment: Seeds are placed in cold moist stratification for 112 days.
Establishment: C. foliosum is found throughout the western United States in moist meadows and upland forests.
Source: npn.rngr.net