Weed Information: Cirsium undulatum (thistle, wavyleaf)
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Cirsium undulatum (thistle, wavyleaf)

Family: Asteraceae

Description

A common native perennial thistle of dry prairies throughout much of the Western U.S. The flowers vary from dark purple to white, but are often pinkish. Note the white, thickened ridge along the backs of the spine-tipped bracts beneath the flowers. Sites occupied by this species are susceptible to invasion by rush skeletonweed.

Characteristics

Flower Color
  • Red (or pink)
  • Purple
  • Red-purple
Inflorescence Type (How the flowers are arranged on the plant)
  • Cyme (simple or branched)
  • Head
  • Solitary, axillary
Number of Petals
  • 0 (no petals)
  • 5 petals
  • more than 10 petals
Petal Separation
  • Completely free to base
  • United > 75% of length
Petal Tip
  • Pointed
Flower Symmetry
  • Flowers regular
Flower Length (Head length in the Asteraceae)
  • 2.5 cm (1.0 inch)
  • 3.0 cm (1.2 inches)
  • 3.5 cm (1.4 inches)
  • 4.0 cm (1.6 inches)
  • 4.5 cm (1.8 inches)
  • 5.0 cm (2.0 inches) or more
Flower Width (Head width in the Asteraceae)
  • 2.5 cm (1.0 inch)
  • 3.0 cm (1.2 inches)
  • 3.5 cm (1.4 inches)
  • 4.0 cm (1.6 inches)
  • 4.5 cm (1.8 inches)
  • 5.0 cm (2.0 inches)
Number of Sepals
  • sepals lacking
  • more than 10 sepals
Sepal Separation
  • Completely free to base
Sepal Tip
  • Pointed
  • Spine-like
Flower Sex
  • Bisexual (perfect)
Number of Styles
  • 1 style
Number of Stamens
  • 5 stamens
Stamens Attached to the Petals
  • Stamens attached to the petals
Stamens Connate (united)
  • Anthers united, syngynoecious

Carpel Separation
  • Carpels united (or one)
Number of Carpels
  • 1 carpel
Ovary Position
  • Inferior (epigynous)
Fruit Type
  • Achene
Fruit Length at Maturity
  • 4 mm (.16 inch)
  • 5 mm (.20 inch)
  • 6 mm (.24 inch)
  • 7 mm (.28 inch)
Fruit Width at Maturity
  • 1 mm (.04 inch) or less
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
Burs
  • Fruit or seed NOT bur-like

Leaf Arrangement
  • Alternate
Leaf Type
  • Simple (including lobed leaves)
Stipules
  • Lacking
Tendrils
  • Tendrils absent
Venation
  • Pinnate
Petiole (leaf stem) Blade Ratio
  • Petiole absent (leaf sessile)
  • Petiole < 25% total length
Leaf Length (blade PLUS petiole)
  • 4 - 10 cm (1.60 - 4.0 inches)
  • 1 - 2 dm (4.0 - 8.0 inches)
  • 2 - 4 dm (8.0 - 16.0 inches)
  • 4 - 6 dm (1.3 - 2.0 feet)
Leaf Width
  • 1 - 2 cm (.40 - .80 inch)
  • 2 - 4 cm (.80 - 1.6 inches)
  • 4 - 10 cm (1.6 - 4.0 inches)
Leaf Shape (simple leaves only)
  • Lanceolate
  • Oblong
  • Oval
  • Pinnately lobed
Leaf or Leaflet Margin
  • Dentate
  • Lobed
  • Parted
  • Undulate (sinuate, repand)
Leaf or Leaflet Blade Base
  • Acute (cuneate)
  • Acuminate (attenuate)
  • Clasping
Leaf or Leaflet Tip
  • Aristate
Leaf or Leaflet Blade Surface
  • Canescent
  • Glabrous (NO hairs)
  • Lower leaf surface more hairy
  • Spiny or prickly
  • Tomentose
Succulence
  • Not succulent

Milky Juice
  • Juice NOT milky (watery)
Woodiness
  • Herbaceous
Spines or Thorns
  • Spines on leaves or stems
  • Spines on flowers\fruits AND leaves\stems
Aromatic (vegetative structures)
  • Not aromatic
Life Cycle
  • Perennial
Growth Habit (while flowering)
  • Erect, columnar (narrow)
Plant Height at Maturity
  • 2 - 4 dm (8.0 - 16.0 inches)
  • 4 - 6 dm (1.3 - 2.0 feet)
  • 6 - 8 dm (2.0 - 2.6 feet)
  • 8 - 10 dm (2.6 - 3.3 feet)
Wind Dissemination
  • Fruit, seed, or spore wind borne
Moisture Regime
  • Mesic
  • Arid
Chlorophyll
  • Present

Stem Cross Section
  • Hollow (flowering stem at maturity)
  • Ridged
  • Round
Flowering Stem Leaves
  • Stem uniformly leafy
Main Stem Branches
  • Main stem branched

Root or Vegetative Propagule
  • Rhizomatous
  • Tap Root

US State
  • Georgia
  • Illinois
  • Kansas
  • Michigan
  • Missouri
  • Mississippi
  • Pennsylvania
  • Texas
  • Wisconsin
  • Indiana
  • Arizona
  • California
  • Colorado
  • Iowa
  • Idaho
  • Minnesota
  • Montana
  • North Dakota
  • New Mexico
  • Nevada
  • Oklahoma
  • Oregon
  • South Dakota
  • Utah
  • Washington
  • Wyoming
  • Nebraska
Canadian Province or Territory
  • British Columbia
  • Alberta
  • Manitoba
  • Saskatchewan

  • Common Weeds of the Canadian Prairies, 1963 (Cat# A53-1136-1) See page: 32
  • Field Guide To The Common Weeds Of Kansas, 1983 (ISBN 0-7006-0233-X) See page: 114
  • Fifty Important Weeds of Montana, Montana Ag. Ext. Service, 1920. 126 pages. See page: 100
  • Nebraska Weeds, 1979 Nebraska Dept. of Ag., Lincoln NE, See page: 193
  • Selected Weeds of Oregon, 1985 and 1989 Supplement (s) Oregon State Dept. of Agriculture, See page: 82
  • South Dakota Weeds 2002 South Dakota Dept. of Ag. 523 E. Capitol, Foss Bldg. Pierre, South Dakota 57501 See page: 215
  • Weed Seeds of the Great Plains, 1993 University of Kansas# 92-125-B ISBN# 0-7006-0651-3 See index #: 211
  • Weeds of California, 1970, State of California Publications and Documents. See page: 454
  • Weeds of California and other Western States, 2007 (ISBN 13: 978-1-879906-69-3) See Page: 272
  • Weeds of Colorado, 1990 Cooperative Extension, Colorado State Univ. Bulletin 521A, See page: 173
  • Weeds of Nebraska and the Great Plains, 1994 (ISBN 0939870-00-4) See page: 118
  • Weeds of the Midwestern United States & Central Canada, University of Georgia 2010, ISBN#0-8203-3506-1 See page: 81
  • Weeds of the West, 1992 (ISBN 0941570-13-4) See page: 116
  • Weeds of the West, 2000 (ISBN 0941570-13-4) See page: 118
  • Listed as a `Weed` by the Biota of North America Program, 2008 X
  • Listed in the WSSA Composite List of Weeds X
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