Weed Information: Amaranthus spinosus (amaranth, spiny)
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Amaranthus spinosus (amaranth, spiny)

Family: Amaranthaceae

Description

Very similar to other erect columnar Amaranthus species but with pairs of straight spines, 1/4 - 1/2 inch long, at the nodes.

Characteristics

Flower Color
  • Green
Inflorescence Type (How the flowers are arranged on the plant)
  • Axillary spikes
  • Terminal spike
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
Sepal Tip
  • Pointed
  • Rounded
Flower Sex
  • Unisexual (monoecious or dioecious)
Number of Styles
  • Styles lacking (male flowers only)
  • 1 style
Number of Stamens
  • stamens lacking (female flowers only)
  • 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
  • 0 (male flowers only or plants producing spores)
  • 1 carpel
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
Burs
  • Fruit or seed NOT bur-like

Leaf Arrangement
  • Alternate
Leaf Type
  • Simple (including lobed leaves)
Stipules
  • Lacking
  • Spines
Tendrils
  • Tendrils absent
Venation
  • Pinnate
Petiole (leaf stem) Blade Ratio
  • Petiole < 25% total length
  • Petiole 25% - 75% total length
Leaf Length (blade PLUS petiole)
  • 2 - 4 cm (.80 - 1.60 inches)
  • 4 - 10 cm (1.60 - 4.0 inches)
Leaf Width
  • 1 - 2 cm (.40 - .80 inch)
  • 2 - 4 cm (.80 - 1.6 inches)
Leaf Shape (simple leaves only)
  • Lanceolate
  • Orbicular (round)
  • Ovate
Leaf or Leaflet Margin
  • Entire
Leaf or Leaflet Blade Base
  • Acute (cuneate)
Leaf or Leaflet Tip
  • Mucronate
  • Rounded (obtuse)
Leaf or Leaflet Blade Surface
  • Glabrous (NO hairs)
  • Sparsely hairy
Succulence
  • Not succulent

Milky Juice
  • Juice NOT milky (watery)
Woodiness
  • Herbaceous
Spines or Thorns
  • Spines on leaves or stems
  • Spines on flowers\fruits AND leaves\stems
Aromatic (vegetative structures)
  • Not aromatic
Life Cycle
  • Annual
Growth Habit (while flowering)
  • Erect, columnar (narrow)
  • Erect, spherical (bushy)
Plant Height at Maturity
  • 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)
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

US State
  • Alabama
  • Arkansas
  • Connecticut
  • Delaware
  • Florida
  • Georgia
  • Illinois
  • Kansas
  • Kentucky
  • Louisiana
  • Massachusetts
  • Maine
  • Michigan
  • Missouri
  • Mississippi
  • North Carolina
  • New Jersey
  • New York
  • Ohio
  • Pennsylvania
  • South Carolina
  • Tennessee
  • Texas
  • Virginia
  • Wisconsin
  • West Virginia
  • Hawaii
  • Indiana
  • Maryland
  • Rhode Island
  • Vermont
  • Arizona
  • California
  • Iowa
  • Minnesota
  • Oklahoma
  • Nebraska
Other
  • Puerto Rico
  • Virgin Islands
  • District of Columbia
Canadian Province or Territory
  • Ontario
  • Manitoba

  • 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: 23
  • How to Know the Weeds, 1972, (ISBN# 0-697-04880-2) See page: 49
  • Identifying Seedling and Mature Weeds (Southeastern US) 1980 North Carolina Agricultural Research Service, Bulletin #461 See page: 98
  • Manual of Ohio Weeds, 1931 Ohio Ag. Exp. Station Bull. # 475, See page: 53
  • Representative Missouri Weeds and Their Control, 1941 Univ. of Missouri Ag. Exp Station Bulletin #433, See page: 79
  • Some Weedy Plants of North Carolina, 1955 North Carolina Ag. Ext. Circular # 390, See page: 20
  • S.W.S.S. Weed ID Guide, 1993 Section Number and Five letter code: 3 AMASP
  • Weed Seeds of the Great Plains, 1993 University of Kansas# 92-125-B ISBN# 0-7006-0651-3 See index #: 25
  • Weeds, 1955 (1980) Walter Conrad Muenscher, ISBN# 0-8014-1266-8 See page: 193, 196
  • Weeds, A Golden Guide, 1972 ISBN#0-307-24353-2 See page: 49
  • Weeds of California and other Western States, 2007 (ISBN 13: 978-1-879906-69-3) See Page: 87
  • Weeds of Kentucky and Adjacent States, 1991 (ISBN 0-8131-1743-7) See page: 214
  • Weeds of the Midwestern United States & Central Canada, University of Georgia 2010, ISBN#0-8203-3506-1 See page: 38
  • Weeds of the North Central States, 1981 Univ. of Illinois, Urbana - Champaign Bulletin # 772, See page: 66
  • Weeds of the Northeast, 1956, Univ. of Delaware Field Manual #1 See species #: 189
  • Weeds of the Northeast, 1997 Cornell University ISBN# 0-8014-8334-4 See page: 96, 363
  • Weeds of the South, University of Georgia 2009, ISBN#0-8203-3046-9 See page: 36
  • Weeds of the Southern United States, 1975, North Carolina Ag. Extension Circular #599 See page: 3
  • Weeds of the United States and Their Control, Lorenzi 1987, ISBN# 0-442-25884-4 See page: 123
  • 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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