Weed Information: Anthemis cotula (chamomile, mayweed)
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Anthemis cotula (chamomile, mayweed)

Family: Asteraceae

Description

This is a common weed of mesic annual cropland. Its most distinctive features include: the small `daisy-like` flower heads with yellow-orange centers and white rays, the finely divided leaves, and the extremely strong and unpleasant odor when the foliage is crushed. In the Pacific Northwest this species is often erroneously referred to as `dog fennel,` a name reserved for Eupatorium capillifolium in the mid-west. In the 2000 edition of Weeds of the West it says `flowers 3/4 inch in diameter.` However, this is actually the measurement of the heads. Similar to Anthemis arvensis and Anthemis austriaca but much more aromatic.

Characteristics

Flower Color
  • Orange
  • Yellow-orange
  • Yellow
  • White
  • Multi-colored
Inflorescence Type (How the flowers are arranged on the plant)
  • Head
  • Panicle
  • Solitary, axillary
  • Solitary, terminal
Number of Petals
  • 5 petals
  • 10 petals
  • more than 10 petals
Petal Separation
  • Completely free to base
  • United > 75% of length
Petal Tip
  • Pointed
  • Rounded
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)
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)
  • 3.5 cm (1.4 inches)
Number of Sepals
  • sepals lacking
  • more than 10 sepals
Sepal Separation
  • Completely free to base
Sepal Tip
  • Rounded
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)
Fruit Width at Maturity
  • 1 mm (.04 inch) or less
Burs
  • Fruit or seed NOT bur-like

Leaf Arrangement
  • Alternate
Leaf Type
  • Pinnately dissected
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)
  • 1 - 2 cm (.40 - .80 inch)
  • 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 or Leaflet Margin
  • Parted
Leaf or Leaflet Blade Base
  • Acute (cuneate)
  • Acuminate (attenuate)
Leaf or Leaflet Tip
  • Acuminate (attenuate)
  • Acute
Leaf or Leaflet Blade Surface
  • Glabrous (NO hairs)
Succulence
  • Not succulent

Milky Juice
  • Juice NOT milky (watery)
Woodiness
  • Herbaceous
Spines or Thorns
  • Spines or Thorns ABSENT
Aromatic (vegetative structures)
  • Aromatic
Life Cycle
  • Annual
Growth Habit (while flowering)
  • Spreading ascending
  • Erect, columnar (narrow)
  • Erect, spherical (bushy)
Plant Height at Maturity
  • 1 - 2 dm (4.0 - 8.0 inches)
  • 2 - 4 dm (8.0 - 16.0 inches)
  • 4 - 6 dm (1.3 - 2.0 feet)
Wind Dissemination
  • Not wind disseminated
Moisture Regime
  • Mesic
Chlorophyll
  • Present

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

Root or Vegetative Propagule
  • Tap Root

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  • Delaware
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  • Maine
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  • New Hampshire
  • New Jersey
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  • Pennsylvania
  • South Carolina
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  • Texas
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Canadian Province or Territory
  • British Columbia
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  • Quebec
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  • Saskatchewan
  • Yukon
Other
  • District of Columbia

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  • Identification Guide to the Weeds of Quebec, 1999 (ISBN# 2-89457-174-7) See page: 67
  • Identifying Seedling and Mature Weeds (Southeastern US) 1980 North Carolina Agricultural Research Service, Bulletin #461 See page: 122
  • Manual of Ohio Weeds, 1931 Ohio Ag. Exp. Station Bull. # 475, See page: 105
  • More Turfgrass and Related Weeds: Beyond the Color Atlas, 2011 Clemson University Publishing ISBN# 978-0-9798777-5-9 See Page: 157
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  • Ontario Weeds, 1992 Agdex 640, Publication #505 See page: 217
  • Representative Missouri Weeds and Their Control, 1941 Univ. of Missouri Ag. Exp Station Bulletin #433, See page: 179
  • Selected Weeds of Oregon, 1985 and 1989 Supplement (s) Oregon State Dept. of Agriculture, See page: 70
  • Some Important Michigan Weeds, 1951 Mich. Ag. Exp. Station Bulletin #304, See page: 211
  • Some Weedy Plants of North Carolina, 1955 North Carolina Ag. Ext. Circular # 390, See page: 51
  • South Dakota Weeds, 1967 South Dakota State University, See page: 195
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  • Weeds of Arkansas 1981 (MP 169-5M-3-81) See page: 8
  • Weeds of California, 1970, State of California Publications and Documents. See page: 425
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  • Weeds of Eastern Washington and Adjacent Areas, 1972 (LOC 72-83635) See page: 268
  • Weeds of Kentucky and Adjacent States, 1991 (ISBN 0-8131-1743-7) See page: 10
  • Weeds of Nebraska and the Great Plains, 1994 (ISBN 0939870-00-4) See page: 74
  • Weeds of New Jersey, 1929 New Jersey Ag. Exp. Station Circular #219, See page: 33
  • Weeds of Nova Scotia, 1986 (ISBN# 0-88871-063) See page: 16
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  • Weeds of the North Central States, 1981 Univ. of Illinois, Urbana - Champaign Bulletin # 772, See page: 186
  • Weeds of the Northeast, 1956, Univ. of Delaware Field Manual #1 See species #: 291
  • Weeds of the Northeast, 1997 Cornell University ISBN# 0-8014-8334-4 See page: 112,128,365
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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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