Weed Information: Rorippa austriaca (fieldcress, Austrian)
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Rorippa austriaca (fieldcress, Austrian)

Family: Brassicaceae

Description

This strongly rhizomatous perennial produces tiny seed pods from 1-2 mm long and wide. The seed is very difficult to clean out of alfalfa seed, and this led to the species being listed as a noxious weed in some states prior to its presence in those states (a rare situation).

Characteristics

Flower Color
  • Yellow
Inflorescence Type (How the flowers are arranged on the plant)
  • Axillary racemes
  • Terminal raceme
Number of Petals
  • 4 petals
Petal Separation
  • Completely free to base
Petal Tip
  • Rounded
Flower Symmetry
  • Flowers regular
Flower Length (Head length in the Asteraceae)
  • 1 mm (.04 inch)
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
  • 4 mm (.16 inch)
Flower Width (Head width in the Asteraceae)
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
  • 4 mm (.16 inch)
Number of Sepals
  • 4 sepals
Sepal Separation
  • Completely free to base
Sepal Tip
  • Pointed
  • Rounded
Flower Sex
  • Bisexual (perfect)
Number of Styles
  • 1 style
Number of Stamens
  • 6 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
  • Superior (hypogynous)
Fruit Type
  • Capsule, 2-celled
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 absent (leaf sessile)
  • Petiole < 25% 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)
Leaf Shape (simple leaves only)
  • Oblanceolate
  • Oblong
Leaf or Leaflet Margin
  • Crenate
  • Dentate
  • Entire
  • Serrate
Leaf or Leaflet Blade Base
  • Acute (cuneate)
  • Clasping
  • Sagittate
Leaf or Leaflet Tip
  • Acute
  • Rounded (obtuse)
Leaf or Leaflet Blade Surface
  • Glabrous (NO hairs)
  • Lower leaf surface more hairy
  • Pubescent
Succulence
  • Not succulent

Milky Juice
  • Juice NOT milky (watery)
Woodiness
  • Herbaceous
Spines or Thorns
  • Spines or Thorns ABSENT
Aromatic (vegetative structures)
  • Not aromatic
  • Aromatic
Life Cycle
  • Perennial
Growth Habit (while flowering)
  • Erect, columnar (narrow)
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)
Wind Dissemination
  • Not wind disseminated
Moisture Regime
  • Aquatic
  • Semi-aquatic
  • Seasonally saturated
  • Mesic
Chlorophyll
  • Present

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

Root or Vegetative Propagule
  • Rhizomatous

US State
  • Kentucky
  • Massachusetts
  • New Hampshire
  • New Jersey
  • New York
  • Pennsylvania
  • Wisconsin
  • California
  • Iowa
  • Idaho
  • Minnesota
  • Montana
  • North Dakota
  • Nevada
  • South Dakota
  • Utah
  • Washington
  • Nebraska
Canadian Province or Territory
  • Alberta
  • Manitoba
  • Saskatchewan

  • Common Weeds of the Canadian Prairies, 1963 (Cat# A53-1136-1) See page: 55
  • South Dakota Weeds, 1967 South Dakota State University, See page: 97
  • Weeds, 1955 (1980) Walter Conrad Muenscher, ISBN# 0-8014-1266-8 See page: 254, 255
  • Weeds of California, 1970, State of California Publications and Documents. See page: 235
  • Weeds of California and other Western States, 2007 (ISBN 13: 978-1-879906-69-3) See Page: 521
  • Weeds of the North Central States, 1981 Univ. of Illinois, Urbana - Champaign Bulletin # 772, See page: 101
  • Weeds of Utah, 1971 UAES Special Report 21, See page: 48
  • 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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