Weed Information: Bidens pilosa
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Bidens pilosa

Common Names: hairy beggarticks = bidens alba

Description

One of the most common Bidens species in the southern United States. Not hardy, but repeatedly introduced (and hence reported) in the Northern U.S. and Canada. Fruits with 2 or 3 sharp, barbed awns. Leaves often soft hairy.

Characteristics

Flower Color
  • Orange
  • Yellow-orange
  • Yellow
  • White
  • Multi-colored
Inflorescence Type (How the flowers are arranged on the plant)
  • Head
  • Panicle
Number of Petals
  • 0 (no petals)
  • 5 petals
  • 6 petals
  • 7 petals
  • 8 petals
  • 9 petals
  • 10 petals
  • more than 10 petals
Petal Separation
  • Completely free to base
  • United > 75% of length
Petal Tip
  • Pointed
  • Rounded
  • Square
  • Toothed
Flower Symmetry
  • Flowers regular
Flower Length (Head length in the Asteraceae)
  • 7 mm (.28 inch)
  • 8 mm (.32 inch)
  • 9 mm (.36 inch)
  • 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)
  • 3.5 cm (1.4 inches)
Flower Width (Head width in the Asteraceae)
  • 7 mm (.28 inch)
  • 8 mm (.32 inch)
  • 9 mm (.36 inch)
  • 1.0 cm (.40 inch)
  • 1.5 cm (.60 inch)
  • 2.0 cm (.80 inch)
  • 2.5 cm (1.0 inch)
Number of Sepals
  • sepals lacking
  • 8 sepals
  • 9 sepals
  • 10 sepals
  • more than 10 sepals
Sepal Separation
  • Completely free to base
Sepal Tip
  • Pointed
  • Rounded
  • 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
  • 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)
  • 2.0 cm (.80 inch)
  • 2.5 cm (1.0 inch)
Fruit Width at Maturity
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
  • 4 mm (.16 inch)
  • 5 mm (.20 inch)
  • 6 mm (.24 inch)
  • 7 mm (.28 inch)
Burs
  • Fruit or seed bur-like

Leaf Arrangement
  • Opposite
  • Whorled 3 per node
Leaf Type
  • Compound even pinnate < 9 leaflets
  • Simple (including lobed leaves)
  • Trifoliolate (3 leaflets)
Stipules
  • Lacking
Tendrils
  • Tendrils absent
Venation
  • Pinnate
Petiole (leaf stem) Blade Ratio
  • Petiole < 25% total length
  • Petiole 25% - 75% 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)
Leaf Width
  • 4 - 10 cm (1.6 - 4.0 inches)
  • 1 - 2 dm (4.0 - 8.0 inches)
Leaf Shape (simple leaves only)
  • Ovate
Leaf or Leaflet Margin
  • Dentate
  • Entire
Leaf or Leaflet Blade Base
  • Acute (cuneate)
  • Rounded
  • Truncate
Leaf or Leaflet Tip
  • Acuminate (attenuate)
  • Acute
Leaf or Leaflet Blade Surface
  • Glabrous (NO hairs)
  • Puberulent
  • Pubescent
  • Tomentose
Succulence
  • Not succulent

Milky Juice
  • Juice NOT milky (watery)
Woodiness
  • Herbaceous
Spines or Thorns
  • Spines or Thorns ABSENT
  • Spines on flowers or fruits only
Aromatic (vegetative structures)
  • Not aromatic
Life Cycle
  • Annual
  • Biennial
Growth Habit (while flowering)
  • Spreading ascending
  • Erect, columnar (narrow)
  • Erect, spherical (bushy)
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)
  • 1 - 1.5 meters (3.3 - 5.0 feet)
  • 1.5 - 2.0 meters (5.0 - 6.6 feet)
Wind Dissemination
  • Not wind disseminated
Moisture Regime
  • Semi-aquatic
  • Seasonally saturated
  • Mesic
Chlorophyll
  • Present

Stem Cross Section
  • Ridged
  • Round
Flowering Stem Leaves
  • Stem uniformly leafy
Main Stem Branches
  • Main stem branched

Root or Vegetative Propagule
  • Rooting at the nodes
  • Tap Root

US State
  • Alabama
  • Connecticut
  • Florida
  • Georgia
  • Kentucky
  • Louisiana
  • Massachusetts
  • Missouri
  • Mississippi
  • North Carolina
  • Pennsylvania
  • South Carolina
  • Texas
  • Wisconsin
  • Hawaii
  • Maryland
  • Arizona
  • California
  • New Mexico
  • Oregon
Other
  • Puerto Rico
  • Virgin Islands
Canadian Province or Territory
  • Ontario
  • Quebec

  • Garden Weeds of Southern California, 1981, See page: 108
  • Weeds of California, 1970, State of California Publications and Documents. See page: 433
  • Weeds of California and other Western States, 2007 (ISBN 13: 978-1-879906-69-3) See Page: 211
  • Weeds of the United States and Their Control, Lorenzi 1987, ISBN# 0-442-25884-4 See page: 300
  • 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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