Elk Thistle

Cirsium foliosum

Native to:
Canada, United States

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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