Weed Information: Senecio vulgaris (groundsel, common)
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Senecio vulgaris (groundsel, common)

Family: Asteraceae

Description

A common annual weed of disturbed sites. The leaves are pinnately lobed, and the small heads of yellow flowers are without ray flowers. The bracts immediately beneath the heads display the small, black tips which are typical of the genus. This species is more toxic to horses than tansy ragwort (Senecio jacobaea) but is seldom consumed in large quantities due to the small stature of the plants.

Characteristics

Flower Color
  • Orange
  • Yellow-orange
  • Yellow
Inflorescence Type (How the flowers are arranged on the plant)
  • Corymb
  • Cyme (simple or branched)
  • Head
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)
  • 4 mm (.16 inch)
  • 5 mm (.20 inch)
  • 6 mm (.24 inch)
  • 7 mm (.28 inch)
  • 8 mm (.32 inch)
  • 9 mm (.36 inch)
Flower Width (Head width in the Asteraceae)
  • 3 mm (.12 inch)
  • 4 mm (.16 inch)
  • 5 mm (.20 inch)
  • 6 mm (.24 inch)
Number of Sepals
  • sepals lacking
  • 10 sepals
  • more than 10 sepals
Sepal Separation
  • Completely free to base
Sepal Tip
  • Pointed
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
  • 1 mm (.04 inch) or less
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
Fruit Width at Maturity
  • 1 mm (.04 inch) or less
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
  • Petiole 25% - 75% total length
Leaf Length (blade PLUS petiole)
  • 2 - 4 cm (.80 - 1.60 inches)
  • 4 - 10 cm (1.60 - 4.0 inches)
Leaf Width
  • 5 - 10 mm (.20 - .40 inch)
  • 1 - 2 cm (.40 - .80 inch)
  • 2 - 4 cm (.80 - 1.6 inches)
Leaf Shape (simple leaves only)
  • Oblanceolate
  • Pinnately lobed
Leaf or Leaflet Margin
  • Dentate
  • Lobed
  • Parted
Leaf or Leaflet Blade Base
  • Acuminate (attenuate)
  • Clasping
Leaf or Leaflet Tip
  • Acute
Leaf or Leaflet Blade Surface
  • Glabrous (NO hairs)
  • Sparsely hairy
Succulence
  • Not succulent

Milky Juice
  • Juice NOT milky (watery)
Woodiness
  • Herbaceous
Spines or Thorns
  • Spines or Thorns ABSENT
Aromatic (vegetative structures)
  • Not aromatic
Life Cycle
  • Annual
Growth Habit (while flowering)
  • Spreading ascending
  • Erect, columnar (narrow)
  • Erect, spherical (bushy)
Plant Height at Maturity
  • 5 - 10 cm (2.0 - 4.0 inches)
  • 1 - 2 dm (4.0 - 8.0 inches)
  • 2 - 4 dm (8.0 - 16.0 inches)
Wind Dissemination
  • Fruit, seed, or spore wind borne
Moisture Regime
  • Seasonally saturated
  • Mesic
Chlorophyll
  • Present

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

Root or Vegetative Propagule
  • Fibrous

US State
  • Alabama
  • Arkansas
  • Connecticut
  • Delaware
  • Florida
  • Georgia
  • Illinois
  • Kansas
  • Kentucky
  • Louisiana
  • Massachusetts
  • Maine
  • Michigan
  • Missouri
  • Mississippi
  • North Carolina
  • New Hampshire
  • New Jersey
  • New York
  • Ohio
  • Pennsylvania
  • South Carolina
  • Tennessee
  • Texas
  • Virginia
  • Wisconsin
  • West Virginia
  • Hawaii
  • Indiana
  • Maryland
  • Rhode Island
  • Vermont
  • Alaska
  • 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
  • New Brunswick
  • Nova Scotia
  • Ontario
  • Prince Edward Island
  • Quebec
  • Alberta
  • Manitoba
  • Newfoundland
  • Saskatchewan
  • Yukon
  • Northwest Territory
Other
  • District of Columbia
  • St. Pierre and Miquelon
  • Labrador
  • Greenland

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  • Weeds of Alberta, 1983 Alberta Environmental Centre Agdex 640-4, See page: 179
  • Weeds of California, 1970, State of California Publications and Documents. See page: 494, 495
  • Weeds of California and other Western States, 2007 (ISBN 13: 978-1-879906-69-3) See Page: 382
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  • Weeds of Eastern Washington and Adjacent Areas, 1972 (LOC 72-83635) See page: 318
  • Weeds of Nova Scotia, 1986 (ISBN# 0-88871-063) See page: 38
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  • Weeds of the Northeast, 1956, Univ. of Delaware Field Manual #1 See species #: 263
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  • Weeds of the West, 2000 (ISBN 0941570-13-4) See page: 170
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  • 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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