Weed Information: Carduus acanthoides (thistle, plumeless)
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Carduus acanthoides (thistle, plumeless)

Family: Asteraceae

Description

These are tall, narrow plants which flower the second year from a rosette. Very weedy in pastures. The common name refers to the fact that the seed parachutes are made from hair-like, rather than feather-like, segments.

Characteristics

Flower Color
  • Purple
  • Red-purple
Inflorescence Type (How the flowers are arranged on the plant)
  • Corymb
  • Cyme (simple or branched)
  • Head
  • Panicle
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)
  • 1.0 cm (.40 inch)
  • 1.5 cm (.6 inch)
  • 2.0 cm (.8 inch)
  • 2.5 cm (1.0 inch)
  • 3.0 cm (1.2 inches)
Flower Width (Head width in the Asteraceae)
  • 1.0 cm (.40 inch)
  • 1.5 cm (.60 inch)
  • 2.0 cm (.80 inch)
  • 2.5 cm (1.0 inch)
  • 3.0 cm (1.2 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
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
  • 4 mm (.16 inch)
  • 5 mm (.20 inch)
Fruit Width at Maturity
  • 1 mm (.04 inch) or less
  • 2 mm (.08 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)
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)
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
  • Pinnately lobed
Leaf or Leaflet Margin
  • Lobed
  • Parted
Leaf or Leaflet Blade Base
  • Clasping
Leaf or Leaflet Tip
  • Aristate
Leaf or Leaflet Blade Surface
  • Lower leaf surface more hairy
  • Sericeous or villous (silky)
  • Spiny or prickly
  • Villous or sericious (silky)
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
  • Biennial
Growth Habit (while flowering)
  • Erect, columnar (narrow)
Plant Height at Maturity
  • 4 - 6 dm (1.3 - 2.0 feet)
  • 6 - 8 dm (2.0 - 2.6 feet)
  • 8 - 10 dm (2.6 - 3.3 feet)
  • 1 - 1.5 meters (3.3 - 5.0 feet)
Wind Dissemination
  • Fruit, seed, or spore wind borne
Moisture Regime
  • Seasonally saturated
  • Mesic
  • Arid
Chlorophyll
  • Present

Stem Cross Section
  • Ridged
  • Round
  • Winged
Flowering Stem Leaves
  • Stem leaves greatly reduced
  • Stem uniformly leafy
Main Stem Branches
  • Main stem branched

Root or Vegetative Propagule
  • Tap Root

US State
  • Connecticut
  • Delaware
  • Illinois
  • Kansas
  • Kentucky
  • Massachusetts
  • Maine
  • Michigan
  • North Carolina
  • New Jersey
  • New York
  • Ohio
  • Pennsylvania
  • Texas
  • Virginia
  • Wisconsin
  • West Virginia
  • Maryland
  • Rhode Island
  • Vermont
  • California
  • Colorado
  • Iowa
  • Idaho
  • Minnesota
  • Montana
  • North Dakota
  • New Mexico
  • Oklahoma
  • South Dakota
  • Washington
  • Wyoming
  • Nebraska
Canadian Province or Territory
  • British Columbia
  • New Brunswick
  • Nova Scotia
  • Ontario
  • Quebec

  • The Biology of Canadian Weeds: Canadian Journal of Plant Science Vol68Pg1053
  • Common Weeds of Canada, Mulligan 1987 (ISBN 0-910053-59-9) See page: 102
  • Nebraska Weeds, 1979 Nebraska Dept. of Ag., Lincoln NE, See page: 186
  • Ontario Weeds, 1992 Agdex 640, Publication #505 See page: 238
  • South Dakota Weeds 2002 South Dakota Dept. of Ag. 523 E. Capitol, Foss Bldg. Pierre, South Dakota 57501 See page: 212
  • Weed Seeds of the Great Plains, 1993 University of Kansas# 92-125-B ISBN# 0-7006-0651-3 See index #: 201
  • Weeds, 1955 (1980) Walter Conrad Muenscher, ISBN# 0-8014-1266-8 See page: 439
  • Weeds and Poisonous Plants of Wyoming and Utah 1987 (ISBN 0-941570-06-1) See page: 156
  • Weeds of California and other Western States, 2007 (ISBN 13: 978-1-879906-69-3) See Page: 217
  • Weeds of Canada, 1970 Canada Dept. of Ag., Pub. # 948, See page: 155
  • Weeds of Nebraska and the Great Plains, 1994 (ISBN 0939870-00-4) See page: 98
  • Weeds of the Midwestern United States & Central Canada, University of Georgia 2010, ISBN#0-8203-3506-1 See page: 71
  • Weeds of the North Central States, 1981 Univ. of Illinois, Urbana - Champaign Bulletin # 772, See page: 198
  • Weeds of the Northern United States and Canada, 1964 Montgomery See page: 175
  • Weeds of the Northern U.S, and Canada, 1999 Royer and Dickinson, (ISBN# 1-55105-221-0) See page: 27
  • Weeds of the United States and Their Control, Lorenzi 1987, ISBN# 0-442-25884-4 See page: 302
  • Weeds of the West, 1992 (ISBN 0941570-13-4) See page: 74
  • Weeds of the West, 2000 (ISBN 0941570-13-4) See page: 78
  • 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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