Weed Information: Ceratophyllum demersum (coontail)
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Ceratophyllum demersum (coontail)

Family: Ceratophyllaceae

Description

Plants totally submerged and rootless, often forming large mats. The leaves narrowly linear, up to 12 per whorl, each leaf finely dissected into linear segments with tiny teeth along the margin. The female flowers form an achene with 2 basal down-turned spines (horns). Another `plant` which might lead to this same ID is Chara which is actually a colonial algae which forms structures which appear similar to coontail due to their whorled linear `leaves.` Upon drying Chara is covered with a white alkaline crust and is very brittle.

Characteristics

Flower Color
  • Green
Inflorescence Type (How the flowers are arranged on the plant)
  • Solitary, axillary
Number of Petals
  • 0 (no petals)
Flower Symmetry
  • Flowers regular
Flower Length (Head length in the Asteraceae)
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
  • 4 mm (.16 inch)
  • 5 mm (.20 inch)
  • 6 mm (.24 inch)
Flower Width (Head width in the Asteraceae)
  • 1 mm (.04 inch)
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
Number of Sepals
  • sepals lacking
Flower Sex
  • Unisexual (monoecious or dioecious)
Number of Styles
  • Styles lacking (male flowers only)
Number of Stamens
  • stamens lacking (female flowers only)
  • more than 10 stamens
Stamens Attached to the Petals
  • Stamens NOT attached to the petals
Stamens Connate (united)
  • Filaments or anthers NOT united

Carpel Separation
  • Carpels united (or one)
Number of Carpels
  • 0 (male flowers only or plants producing spores)
  • 1 carpel
Ovary Position
  • Superior (hypogynous)
Fruit Type
  • Achene
Fruit Length at Maturity
  • 4 mm (.16 inch)
  • 5 mm (.20 inch)
  • 6 mm (.24 inch)
Fruit Width at Maturity
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
  • 4 mm (.16 inch)
Burs
  • Fruit or seed NOT bur-like

Leaf Arrangement
  • Whorled > 8 per node
Leaf Type
  • Pinnately dissected
Stipules
  • Lacking
Tendrils
  • Tendrils absent
Petiole (leaf stem) Blade Ratio
  • Petiole absent (leaf sessile)
Leaf Length (blade PLUS petiole)
  • 1 - 2 cm (.40 - .80 inch)
  • 2 - 4 cm (.80 - 1.60 inches)
Leaf Width
  • < 1 mm (< .04 inch)
Leaf Shape (simple leaves only)
  • Linear or filiform
Leaf or Leaflet Margin
  • Entire
  • Parted
  • Serrate, doubly
Leaf or Leaflet Blade Base
  • Acute (cuneate)
Leaf or Leaflet Tip
  • Acute
  • Rounded (obtuse)
Leaf or Leaflet Blade Surface
  • Antrorsely pubescent
  • Glabrous (NO hairs)
  • Pubescent
  • 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
Life Cycle
  • Annual
  • Biennial
  • Perennial
Growth Habit (while flowering)
  • Erect, columnar (narrow)
  • Erect, spherical (bushy)
  • Submerged (mostly or totally)
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
  • Aquatic
Chlorophyll
  • Present

Stem Cross Section
  • 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
  • Saskatchewan
  • Yukon
  • Northwest Territory
Other
  • Puerto Rico
  • Virgin Islands
  • District of Columbia

  • Aquatic and Riparian Plants of the West, 2003 (ISBN# 1-879906-59-7) See page: 78
  • Common Weeds of the United States, 1971 (ISBN 0-486-20504-5) See page: 170
  • Weeds of the Northern U.S, and Canada, 1999 Royer and Dickinson, (ISBN# 1-55105-221-0) See page: 212 - 213
  • Weeds of the United States and Their Control, Lorenzi 1987, ISBN# 0-442-25884-4 See page: 138
  • 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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