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Similar but less problematic plants:
Agastache 'Blue Fortune' Form
Cirsium arvense is often confused with:
Eryngium planum Eryngium
Eryngium yuccifolium In the summer.
Plants that fill a similar niche:
Impatiens hawkeri Impatiens hawkeri
Verbena canadensis Verbena canadensis
Viola sororia Viola papilionacea

Swamp Thistle Cirsium arvense

Other plants called Swamp Thistle:

Previously known as:

  • Carduus muticus
  • Cirsium muticum
Phonetic Spelling
SIR-see-um ar-VEN-see
Description

Canada Thistle is an upright herbaceous perennial weed in the Asteraceae (daisy) family.  It is native to Europe, Asia, and Africa where it is found in wet meadows, swamps, bogs, and moist woodlands. It was introduced to the United States in the 1600's and is considered a noxious weed in 43 states including North Carolina.  It is found in most of the US and southern Canada.  Stems are upright up to 6' tall, grooved, and just a few hairs or none. The stems are also slender and branched only at the top. The leaves are poky like other thistles and it has purple pink flowers that appear in the summer. Canada thistle has male and female flowers on separate plants, but the flowers look similar to each other. Male flowers will not produce seeds, female flowers are fragrant. 

It prefers moist soil, sun to partial shade but withstands a variety of soil conditions and is most commonly found in disturbed areas, clearings or agricultural sites.  Canada thistle spreads through both seeds and budding from underground roots. 

The common name Creeping thistle comes from its tendency to spread by lateral root growth, or its seeds are wind dispersed allowing it to rapidly form dense stands that can shade out native plants.  Its root system can extend more than fifteen feet out and six feet down from the plant, making management difficult as new plants come up from the roots. 

Canada thistle or creeping thistle is a noxious weed that is difficult to manage.  It does not need to be introduced into the garden. 

Insects, Diseases, and Other Plant Problems:  Canada Thistles extensive and aggressive root and shoot system coupled with its prolific seed production make it very difficult to manage.  Consistent repeated mowing and/or hand pulling can deplete the root system storage over a series of years.   Biological and chemical management may need to be used in conjunction with mechanical measures.

See this plant in the following landscape:
Cultivars / Varieties:
Tags:
#purple#full sun tolerant#lavender#perennials#white flowers#weedy#fall interest#aggressive#summer flowers#wind dispersed seeds#disturbed areas#spring interest#perennial weeds#bird friendly#partial shade tolerant
 
Cultivars / Varieties:
Tags:
#purple#full sun tolerant#lavender#perennials#white flowers#weedy#fall interest#aggressive#summer flowers#wind dispersed seeds#disturbed areas#spring interest#perennial weeds#bird friendly#partial shade tolerant
  • Attributes:
    Genus:
    Cirsium
    Species:
    arvense
    Family:
    Asteraceae
    Uses (Ethnobotany):
    The feathery pappus from the fruits was used by the Cherokee as fletching on their blow darts.
    Life Cycle:
    Perennial
    Recommended Propagation Strategy:
    Seed
    Country Or Region Of Origin:
    Eurasia, Northwestern Africa
    Distribution:
    Most of the US and southern Canada
    Wildlife Value:
    The seeds are rich in oil, an important food source for seed-eating birds.
  • Whole Plant Traits:
    Plant Type:
    Herbaceous Perennial
    Perennial
    Weed
    Habit/Form:
    Erect
    Growth Rate:
    Rapid
    Maintenance:
    High
    Texture:
    Coarse
    Appendage:
    Prickles
    Spines
  • Cultural Conditions:
    Light:
    Full sun (6 or more hours of direct sunlight a day)
    Partial Shade (Direct sunlight only part of the day, 2-6 hours)
    Soil Texture:
    Clay
    High Organic Matter
    Loam (Silt)
    Sand
    Soil pH:
    Alkaline (>8.0)
    Neutral (6.0-8.0)
    Soil Drainage:
    Moist
    Occasionally Dry
    Occasionally Wet
    Very Dry
    Available Space To Plant:
    12 inches-3 feet
    NC Region:
    Mountains
    USDA Plant Hardiness Zone:
    4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b
  • Fruit:
    Fruit Color:
    Cream/Tan
    Display/Harvest Time:
    Fall
    Fruit Type:
    Achene
    Fruit Length:
    < 1 inch
    Fruit Width:
    < 1 inch
    Fruit Description:
    Tiny dry 0.1" long with feathery white to light brown pappus
  • Flowers:
    Flower Color:
    Pink
    Purple/Lavender
    White
    Flower Inflorescence:
    Head
    Flower Value To Gardener:
    Fragrant
    Flower Bloom Time:
    Summer
    Flower Shape:
    Dome
    Flower Petals:
    Bracts
    Flower Size:
    < 1 inch
    Flower Description:
    There are male and female plants. Female flowers have a scent and male flowers do not. Pink, deep lavender, or white flowers; bracts are tomentose without spines. Flowering occurs from June-August and an average flower produces 2000 seeds per plant.
  • Leaves:
    Leaf Color:
    Green
    Leaf Feel:
    Prickly
    Leaf Type:
    Simple
    Leaf Arrangement:
    Alternate
    Rosulate
    Leaf Shape:
    Elliptical
    Lanceolate
    Oblong
    Leaf Margin:
    Lobed
    Hairs Present:
    Yes
    Leaf Length:
    3-6 inches
    Leaf Width:
    1-3 inches
    Leaf Description:
    Dark green, deeply lobed, elliptic to oblong-lanceolate leaves 2"-6" long (5"-8" basal leaves) sometimes slightly clasping the stems; tomentose below and very prickly.
  • Stem:
    Stem Color:
    Green
    Stem Is Aromatic:
    No
    Stem Surface:
    Hairy (pubescent)
    Stem Description:
    Slender, smooth, grooved stems that sometimes have short hairs. Stems do not have conspicuous spines.
  • Landscape:
    Attracts:
    Songbirds
    Problems:
    Spines/Thorns
    Weedy