Weed Information: Silphium laciniatum (compassplant)
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Silphium laciniatum (compassplant)

Family: Asteraceae

Description

The common name of compassplant comes from the fact that the basal leaves are usually aligned north and south. The specific name `laciniatum` means `divided into many long narrow segments` and describes the leaf margin.

Characteristics

Flower Color
  • Yellow
Inflorescence Type (How the flowers are arranged on the plant)
  • Head
  • Terminal raceme
Number of Petals
  • 5 petals
Petal Separation
  • Completely free to base
  • United > 75% of length
Petal Tip
  • Rounded
  • Toothed
Flower Symmetry
  • Flowers regular
Flower Length (Head length in the Asteraceae)
  • 2.0 cm (.8 inch)
  • 2.5 cm (1.0 inch)
  • 3.0 cm (1.2 inches)
  • 3.5 cm (1.4 inches)
  • 4.0 cm (1.6 inches)
Flower Width (Head width in the Asteraceae)
  • > 5.0 cm (> 2.0 inches)
Number of Sepals
  • sepals lacking
  • 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
  • 6 mm (.24 inch)
  • 7 mm (.28 inch)
  • 8 mm (.32 inch)
  • 9 mm (.36 inch)
  • 1.0 cm (.40 inch)
  • 1.5 cm (.60 inch)
Fruit Width at Maturity
  • 4 mm (.16 inch)
  • 5 mm (.20 inch)
  • 6 mm (.24 inch)
  • 7 mm (.28 inch)
  • 8 mm (.32 inch)
Burs
  • Fruit or seed NOT bur-like

Leaf Arrangement
  • Alternate
Leaf Type
  • Pinnately dissected
  • 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)
  • 1 - 2 dm (4.0 - 8.0 inches)
  • 2 - 4 dm (8.0 - 16.0 inches)
Leaf Width
  • 1 - 2 dm (4.0 - 8.0 inches)
Leaf Shape (simple leaves only)
  • Pinnately lobed
Leaf or Leaflet Margin
  • Lobed
  • Parted
Leaf or Leaflet Blade Base
  • Acute (cuneate)
  • Acuminate (attenuate)
Leaf or Leaflet Tip
  • Acuminate (attenuate)
  • Acute
Leaf or Leaflet Blade Surface
  • Glandular
  • Hirsute
  • Hispid or setose
  • Scabrous (like sand paper)
Succulence
  • Not succulent

Milky Juice
  • Juice NOT milky (watery)
Woodiness
  • Herbaceous
Spines or Thorns
  • Spines or Thorns ABSENT
Aromatic (vegetative structures)
  • Not aromatic
  • Aromatic
Life Cycle
  • Perennial
Growth Habit (while flowering)
  • Erect, columnar (narrow)
Plant Height at Maturity
  • 1 - 1.5 meters (3.3 - 5.0 feet)
  • 1.5 - 2.0 meters (5.0 - 6.6 feet)
  • 2 - 2.5 meters (6.6 - 8.3 feet)
  • 2.5 - 5 meters (8.3 - 16.6 feet)
Wind Dissemination
  • Not wind disseminated
  • Fruit, seed, or spore wind borne
Moisture Regime
  • Mesic
  • Arid
Chlorophyll
  • Present

Stem Cross Section
  • Hollow (flowering stem at maturity)
  • Round
Flowering Stem Leaves
  • Stem leaves greatly reduced
Main Stem Branches
  • Main stem unbranched
  • Main stem branched

Root or Vegetative Propagule
  • Tap Root

US State
  • Alabama
  • Arkansas
  • Illinois
  • Kansas
  • Kentucky
  • Louisiana
  • Michigan
  • Missouri
  • Mississippi
  • New York
  • Ohio
  • Pennsylvania
  • Tennessee
  • Texas
  • Virginia
  • Wisconsin
  • Indiana
  • Colorado
  • Iowa
  • Minnesota
  • North Dakota
  • New Mexico
  • Oklahoma
  • South Dakota
  • Nebraska
Other
  • District of Columbia
Canadian Province or Territory
  • Ontario

  • Field Guide To The Common Weeds Of Kansas, 1983 (ISBN 0-7006-0233-X) See page: 124
  • Nebraska Weeds, 1979 Nebraska Dept. of Ag., Lincoln NE, See page: 215
  • Weed Seeds of the Great Plains, 1993 University of Kansas# 92-125-B ISBN# 0-7006-0651-3 See index #: 239
  • 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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