Weed Information: Amaranthus blitoides (pigweed, prostrate)
Back to Plant List

Amaranthus blitoides (pigweed, prostrate)

Family: Amaranthaceae

Description

Plants prostrate with small clusters of flowers in the leaf axils. The seeds are relatively large (1.5 mm) in comparison to many of the other pigweeds whose seeds average only 1 mm. As with all members of the genus, the flowers are small, green, and subtended by small spines.

Characteristics

Flower Color
  • Green
Inflorescence Type (How the flowers are arranged on the plant)
  • Axillary cluster
Number of Petals
  • 0 (no petals)
Flower Symmetry
  • Flowers regular
Flower Length (Head length in the Asteraceae)
  • < 1 mm (< .04 inch)
  • 1 mm (.04 inch)
  • 2 mm (.08 inch)
Flower Width (Head width in the Asteraceae)
  • < 1 mm (< .04 inch)
  • 1 mm (.04 inch)
  • 2 mm (.08 inch)
Number of Sepals
  • 5 sepals
Sepal Separation
  • Completely free to base
  • United at base < 25% length
Sepal Tip
  • Pointed
Flower Sex
  • Unisexual (monoecious or dioecious)
Number of Styles
  • Styles lacking (male flowers only)
  • 1 style
Number of Stamens
  • stamens lacking (female flowers only)
  • 3 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)
  • 3 carpels
Ovary Position
  • Superior (hypogynous)
Fruit Type
  • Utricle
Fruit Length at Maturity
  • 1 mm (.04 inch) or less
  • 2 mm (.08 inch)
Fruit Width at Maturity
  • 1 mm (.04 inch) or less
  • 2 mm (.08 inch)
Burs
  • Fruit or seed NOT bur-like

Leaf Arrangement
  • Alternate
Leaf Type
  • Simple (including lobed leaves)
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)
  • 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 Shape (simple leaves only)
  • Elliptic
  • Oblanceolate
  • Obovate
  • Oval
  • Ovate
Leaf or Leaflet Margin
  • Entire
Leaf or Leaflet Blade Base
  • Acute (cuneate)
  • Acuminate (attenuate)
Leaf or Leaflet Tip
  • Notched (emarginate, retuse)
  • Acute
  • Rounded (obtuse)
Leaf or Leaflet Blade Surface
  • Glabrous (NO hairs)
  • Puberulent
  • Pubescent
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
Growth Habit (while flowering)
  • Prostrate
  • Spreading ascending
Plant Height at Maturity
  • 1 - 5 cm (.40 - 2.0 inches)
  • 5 - 10 cm (2.0 - 4.0 inches)
  • 1 - 2 dm (4.0 - 8.0 inches)
Wind Dissemination
  • Not wind disseminated
Moisture Regime
  • Mesic
  • Arid
Chlorophyll
  • Present

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

Root or Vegetative Propagule
  • Tap Root

US State
  • Alabama
  • Arkansas
  • Connecticut
  • Delaware
  • Florida
  • Georgia
  • Illinois
  • Kansas
  • Kentucky
  • Louisiana
  • Massachusetts
  • Maine
  • Michigan
  • Missouri
  • 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
  • Ontario
  • Quebec
  • Alberta
  • Manitoba
  • Saskatchewan
Other
  • District of Columbia

  • An Illustrated Guide To Arizona Weeds, 1972 (ISBN 0-8165-0288-9) 338 pages. See page: 114
  • The Biology of Canadian Weeds: Canadian Journal of Plant Science Vol83Pg1039
  • California Growers Weed Identification Handbook, 1968 - 1998 University of California Publication # 4030-1, See page: 57
  • Common Weeds of the Canadian Prairies, 1963 (Cat# A53-1136-1) See page: 22
  • Common Weeds of the United States, 1971 (ISBN 0-486-20504-5) See page: 144
  • Common Weed Seedlings of the United States and Canada, 1978 Coop Ext. Univ. of Georgia, Athens, See page: 6
  • Field Guide To The Common Weeds Of Kansas, 1983 (ISBN 0-7006-0233-X) See page: 21
  • Garden Weeds of Southern California, 1981, See page: 36
  • Gilkey`s Weeds of the Pacific Northwest, 1980 (ISBN 0-88246-039-0) See page: 89
  • How to Know the Weeds, 1972, (ISBN# 0-697-04880-2) See page: 51
  • Manual of Ohio Weeds, 1931 Ohio Ag. Exp. Station Bull. # 475, See page: 54
  • Nebraska Weeds, 1979 Nebraska Dept. of Ag., Lincoln NE, See page: 59
  • Ontario Weeds, 1992 Agdex 640, Publication #505 See page: 65
  • Representative Missouri Weeds and Their Control, 1941 Univ. of Missouri Ag. Exp Station Bulletin #433, See page: 79
  • South Dakota Weeds, 1967 South Dakota State University, See page: 78
  • South Dakota Weeds 2002 South Dakota Dept. of Ag. 523 E. Capitol, Foss Bldg. Pierre, South Dakota 57501 See page: 75
  • S.W.S.S. Weed ID Guide, 1993 Section Number and Five letter code: 3 AMABL
  • Weed Seeds of the Great Plains, 1993 University of Kansas# 92-125-B ISBN# 0-7006-0651-3 See index #: 20
  • Weeds, 1955 (1980) Walter Conrad Muenscher, ISBN# 0-8014-1266-8 See page: 192, 193
  • Weeds, A Golden Guide, 1972 ISBN#0-307-24353-2 See page: 49
  • Weeds and Poisonous Plants of Wyoming and Utah 1987 (ISBN 0-941570-06-1) See page: 30
  • Weeds of California, 1970, State of California Publications and Documents. See page: 160, 161
  • Weeds of California and other Western States, 2007 (ISBN 13: 978-1-879906-69-3) See Page: 78
  • Weeds of Canada, 1970 Canada Dept. of Ag., Pub. # 948, See page: 55
  • Weeds of Colorado, 1990 Cooperative Extension, Colorado State Univ. Bulletin 521A, See page: 66
  • Weeds of Eastern Washington and Adjacent Areas, 1972 (LOC 72-83635) See page: 98
  • Weeds of Nebraska and the Great Plains, 1994 (ISBN 0939870-00-4) See page: 34
  • Weeds of the Midwestern United States & Central Canada, University of Georgia 2010, ISBN#0-8203-3506-1 See page: 33
  • Weeds of the North Central States, 1981 Univ. of Illinois, Urbana - Champaign Bulletin # 772, See page: 63
  • Weeds of the Northeast, 1997 Cornell University ISBN# 0-8014-8334-4 See page: 90, 92, 363
  • Weeds of the Northern United States and Canada, 1964 Montgomery See page: 41
  • Weeds of the Northern U.S, and Canada, 1999 Royer and Dickinson, (ISBN# 1-55105-221-0) See page: 4
  • Weeds of the Prairies, 2000 Alberta Food and Agriculture ISBN# 0-7732-6147-8 See page: 224
  • Weeds of the South, University of Georgia 2009, ISBN#0-8203-3046-9 See page: 32
  • Weeds of the West, 1992 (ISBN 0941570-13-4) See page: 8
  • Weeds of the West, 2000 (ISBN 0941570-13-4) See page: 8
  • Weeds of Utah, 1971 UAES Special Report 21, See page: 34
  • Listed as a `Weed` by the Biota of North America Program, 2008 X
  • Listed in the WSSA Composite List of Weeds X
Back to Plant List