Weed Information: Persicaria amphibia (smartweed, water)
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Persicaria amphibia (smartweed, water)

Family: Polygonaceae

Description

In water or wet soil. Flowers pink, plants rooting at the nodes. The membranous stipules occasionally with a herbaceous `skirt` arising from the upper margin. Polygonum amphibium var. emersum = Polygonum muhlenbergia, Polygonum coccineum.

Characteristics

Flower Color
  • Red (or pink)
Inflorescence Type (How the flowers are arranged on the plant)
  • Head
  • Panicle
  • Terminal raceme
  • Terminal spike
Number of Petals
  • 0 (no petals)
  • 5 petals
Petal Separation
  • Completely free to base
  • United at base only (<25% length)
  • United from 25% - 75% length
Petal Tip
  • Pointed
  • Rounded
Flower Symmetry
  • Flowers regular
Flower Length (Head length in the Asteraceae)
  • 4 mm (.16 inch)
  • 5 mm (.20 inch)
Flower Width (Head width in the Asteraceae)
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
  • 4 mm (.16 inch)
Number of Sepals
  • sepals lacking
  • 5 sepals
Sepal Separation
  • United at base < 25% length
  • United from 25% - 75% length
Sepal Tip
  • Pointed
  • Rounded
Flower Sex
  • Bisexual (perfect)
Number of Styles
  • 2 styles
  • 3 styles
Number of Stamens
  • 8 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
  • 3 carpels
Ovary Position
  • Superior (hypogynous)
Fruit Type
  • Achene
Fruit Length at Maturity
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
Fruit Width at Maturity
  • 1 mm (.04 inch) or less
Burs
  • Fruit or seed NOT bur-like

Leaf Arrangement
  • Alternate
Leaf Type
  • Simple (including lobed leaves)
Stipules
  • Foliaceous 4-10 mm (.16 - .40 in) long
  • Membranous, entire
  • Membranous, laciniate
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)
Leaf Width
  • 2 - 4 cm (.80 - 1.6 inches)
  • 4 - 10 cm (1.6 - 4.0 inches)
Leaf Shape (simple leaves only)
  • Elliptic
  • Lanceolate
  • Oblanceolate
  • Oblong
  • Ovate
Leaf or Leaflet Margin
  • Entire
Leaf or Leaflet Blade Base
  • Acute (cuneate)
  • Cordate
Leaf or Leaflet Tip
  • Acute
Leaf or Leaflet Blade Surface
  • Glabrous (NO hairs)
  • Hispid or setose
  • Strigose
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
  • Perennial
Growth Habit (while flowering)
  • Prostrate
  • Spreading ascending
  • Erect, columnar (narrow)
  • Floating
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)
  • 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
  • Semi-aquatic
  • Seasonally saturated
Chlorophyll
  • Present

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

Root or Vegetative Propagule
  • Fibrous
  • Rhizomatous
  • Rooting at the nodes

US State
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  • Arizona
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Canadian Province or Territory
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  • Yukon
  • Nunavut
  • Northwest Territory
Other
  • District of Columbia
  • St. Pierre and Miquelon
  • Labrador

  • Aquatic and Riparian Plants of the West, 2003 (ISBN# 1-879906-59-7) See page: 314
  • California Growers Weed Identification Handbook, 1968 - 1998 University of California Publication # 4030-1, See page: 94
  • Common Weeds of the United States, 1971 (ISBN 0-486-20504-5) See page: 114, 118
  • Field Guide To The Common Weeds Of Kansas, 1983 (ISBN 0-7006-0233-X) See page: 29
  • How to Know the Weeds, 1972, (ISBN# 0-697-04880-2) See page: 57
  • Nebraska Weeds, 1979 Nebraska Dept. of Ag., Lincoln NE, See page: 49
  • Ontario Weeds, 1992 Agdex 640, Publication #505 See page: 56, 57
  • Representative Missouri Weeds and Their Control, 1941 Univ. of Missouri Ag. Exp Station Bulletin #433, See page: 69
  • Some Important Michigan Weeds, 1951 Mich. Ag. Exp. Station Bulletin #304, See page: 77
  • South Dakota Weeds, 1967 South Dakota State University, See page: 74
  • South Dakota Weeds 2002 South Dakota Dept. of Ag. 523 E. Capitol, Foss Bldg. Pierre, South Dakota 57501 See page: 69
  • S.W.S.S. Weed ID Guide, 1993 Section Number and Five letter code: 6 POLCC
  • Weed Seeds of the Great Plains, 1993 University of Kansas# 92-125-B ISBN# 0-7006-0651-3 See index #: 35
  • Weeds, 1955 (1980) Walter Conrad Muenscher, ISBN# 0-8014-1266-8 See page: 166
  • Weeds, A Golden Guide, 1972 ISBN#0-307-24353-2 See page: 41, 42
  • Weeds of California, 1970, State of California Publications and Documents. See page: 134, 135
  • Weeds of California and other Western States, 2007 (ISBN 13: 978-1-879906-69-3) See Page: 1319
  • Weeds of Nebraska and the Great Plains, 1994 (ISBN 0939870-00-4) See page: 474
  • Weeds of the Midwestern United States & Central Canada, University of Georgia 2010, ISBN#0-8203-3506-1 See page: 259
  • Weeds of the North Central States, 1981 Univ. of Illinois, Urbana - Champaign Bulletin # 772, See page: 50
  • Weeds of the Northern U.S, and Canada, 1999 Royer and Dickinson, (ISBN# 1-55105-221-0) See page: 87
  • Weeds of the South, University of Georgia 2009, ISBN#0-8203-3046-9 See page: 256
  • Weeds of the West, 1992 (ISBN 0941570-13-4) See page: 511
  • Weeds of the West, 2000 (ISBN 0941570-13-4) See page: 507
  • 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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