Weed Information: Heracleum maximum (parsnip, cow)
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Heracleum maximum (parsnip, cow)

Family: Apiaceae

Description

Cow parsnip is a native plant of moist, rich soils in the Western U.S. Its populations have fallen dramatically since the European colonization of the west due to the fact that this species will not survive cultivation or grazing by cattle. Despite the fact that this species is not at all weedy, it often appears in weed books, most likely because it is easily identified and photographed.

Characteristics

Flower Color
  • White
Inflorescence Type (How the flowers are arranged on the plant)
  • Compound umbel
Number of Petals
  • 5 petals
Petal Separation
  • Completely free to base
Petal Tip
  • Bilobed
  • Rounded
Flower Symmetry
  • Flowers regular
  • Flowers slightly irregular
Flower Length (Head length in the Asteraceae)
  • 3 mm (.12 inch)
  • 4 mm (.16 inch)
  • 5 mm (.20 inch)
  • 6 mm (.24 inch)
  • 7 mm (.28 inch)
Flower Width (Head width in the Asteraceae)
  • 5 mm (.20 inch)
  • 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)
Number of Sepals
  • sepals lacking
  • 5 sepals
Sepal Separation
  • United at base < 25% length
Sepal Tip
  • Pointed
Flower Sex
  • Bisexual (perfect)
Number of Styles
  • 2 styles
Number of Stamens
  • 5 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
  • 2 carpels
Ovary Position
  • Inferior (epigynous)
Fruit Type
  • Schizocarp
Fruit Length at Maturity
  • 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
  • 5 mm (.20 inch)
  • 6 mm (.24 inch)
  • 7 mm (.28 inch)
  • 8 mm (.32 inch)
  • 9 mm (.36 inch)
Burs
  • Fruit or seed NOT bur-like

Leaf Arrangement
  • Alternate
Leaf Type
  • Palmately dissected
  • Trifoliolate (3 leaflets)
Stipules
  • Lacking
Tendrils
  • Tendrils absent
Venation
  • Palmate
Petiole (leaf stem) Blade Ratio
  • Petiole 25% - 75% total length
Leaf Length (blade PLUS petiole)
  • 2 - 4 dm (8.0 - 16.0 inches)
  • 4 - 6 dm (1.3 - 2.0 feet)
  • > 6 dm (> 2.0 feet)
Leaf Width
  • 2 - 4 dm (8.0 - 16.0 inches)
  • > 4 dm (>1.3 feet)
Leaf Shape (simple leaves only)
  • Lyrate
Leaf or Leaflet Margin
  • Dentate
  • Lobed
  • Parted
Succulence
  • Succulent
  • Not succulent
Leaf or Leaflet Blade Base
  • Acuminate (attenuate)
  • Clasping
  • Cordate
  • Truncate
Leaf or Leaflet Tip
  • Acute
Leaf or Leaflet Blade Surface
  • Pubescent
  • Sericeous or villous (silky)
  • Tomentose
  • Villous or sericious (silky)

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

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

Root or Vegetative Propagule
  • Fibrous
  • Tap Root

US State
  • Connecticut
  • Delaware
  • Georgia
  • Illinois
  • Kansas
  • Kentucky
  • Massachusetts
  • Maine
  • Michigan
  • Missouri
  • North Carolina
  • New Hampshire
  • New Jersey
  • New York
  • Ohio
  • Pennsylvania
  • Tennessee
  • Virginia
  • Wisconsin
  • West Virginia
  • Indiana
  • Maryland
  • Rhode Island
  • Vermont
  • Alaska
  • Arizona
  • California
  • Colorado
  • Iowa
  • Idaho
  • Minnesota
  • Montana
  • North Dakota
  • New Mexico
  • Nevada
  • 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
  • Nunavut
  • Northwest Territory
Other
  • St. Pierre and Miquelon
  • Labrador

  • Aquatic and Riparian Plants of the West, 2003 (ISBN# 1-879906-59-7) See page: 158
  • California Growers Weed Identification Handbook, 1968 - 1998 University of California Publication # 4030-1, See page: 256
  • Gilkey`s Weeds of the Pacific Northwest, 1980 (ISBN 0-88246-039-0) See page: 205
  • Manual of Ohio Weeds, 1931 Ohio Ag. Exp. Station Bull. # 475, See page: 86
  • Northwest Weeds, 1990 (ISBN 0-87842-249-8) See page: 82
  • Ontario Weeds, 1992 Agdex 640, Publication #505 See page: 156
  • Selected Weeds of Oregon, 1985 and 1989 Supplement (s) Oregon State Dept. of Agriculture, See page: 51
  • Weeds and Poisonous Plants of Wyoming and Utah 1987 (ISBN 0-941570-06-1) See page: 98
  • Weeds of California, 1970, State of California Publications and Documents. See page: 326, 329
  • Weeds of the West, 1992 (ISBN 0941570-13-4) See page: 26
  • Weeds of the West, 2000 (ISBN 0941570-13-4) See page: 26
  • Listed as a `Weed` by the Biota of North America Program, 2008 x
  • Herniaria hirsuta ssp. cinerea / Caryophyllaceae / herniaria, gray
  • California Growers Weed Identification Handbook, 1968 - 1998 University of California Publication # 4030-1, See page: 208
  • Weeds of California, 1970, State of California Publications and Documents. See page: 178
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