Weed Information: Lythrum hyssopifolium (loosestrife, hyssop)
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Lythrum hyssopifolium (loosestrife, hyssop)

Family: Lythraceae

Description

Also known as `grass poly.` This native weed varies from an annual to a stoloniferous perennial. It is one of very few dicots (`broadleaves`) which can have six petals.

Characteristics

Flower Color
  • Red (or pink)
  • Purple
  • Red-purple
  • White
Inflorescence Type (How the flowers are arranged on the plant)
  • Solitary, axillary
Number of Petals
  • 4 petals
  • 5 petals
  • 6 petals
  • 7 petals
Petal Separation
  • Completely free to base
Petal Tip
  • Rounded
Flower Symmetry
  • Flowers regular
Flower Length (Head length in the Asteraceae)
  • 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)
  • 5 mm (.20 inch)
Number of Sepals
  • 4 sepals
  • 5 sepals
  • 6 sepals
  • 7 sepals
Sepal Separation
  • United > 75% of length
Sepal Tip
  • Pointed
Flower Sex
  • Bisexual (perfect)
Number of Styles
  • 1 style
Number of Stamens
  • 4 stamens
  • 5 stamens
  • 6 stamens
  • 7 stamens
  • 8 stamens
  • 9 stamens
  • 10 stamens
  • more than 10 stamens
Stamens Attached to the Petals
  • Stamens attached to the petals
Stamens Connate (united)
  • Filaments or anthers NOT united

Carpel Separation
  • Carpels united (or one)
Number of Carpels
  • 1 carpel
  • 2 carpels
Ovary Position
  • Halfway (perigynous)
  • Inferior (epigynous)
Fruit Type
  • Capsule, 2-celled
Fruit Length at Maturity
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
  • 4 mm (.16 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
  • Opposite
  • Whorled 3 per node
Leaf Type
  • Simple (including lobed leaves)
Stipules
  • Lacking
Tendrils
  • Tendrils absent
Venation
  • Pinnate
Petiole (leaf stem) Blade Ratio
  • Petiole absent (leaf sessile)
Leaf Length (blade PLUS petiole)
  • 5 - 10 mm (.20 - .40 inch)
  • 1 - 2 cm (.40 - .80 inch)
Leaf Width
  • 1 - 5 mm (.04 - .20 inch)
  • 5 - 10 mm (.20 - .40 inch)
Leaf Shape (simple leaves only)
  • Lanceolate
  • Linear or filiform
Leaf or Leaflet Margin
  • Entire
Leaf or Leaflet Blade Base
  • Acute (cuneate)
  • Rounded
  • Truncate
Leaf or Leaflet Tip
  • Acute
Leaf or Leaflet Blade Surface
  • Glabrous (NO hairs)
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
  • Annual
  • Biennial
  • Perennial
Growth Habit (while flowering)
  • Prostrate
  • Spreading ascending
  • Erect, columnar (narrow)
  • Erect, spherical (bushy)
Plant Height at Maturity
  • 5 - 10 cm (2.0 - 4.0 inches)
  • 1 - 2 dm (4.0 - 8.0 inches)
  • 2 - 4 dm (8.0 - 16.0 inches)
  • 4 - 6 dm (1.3 - 2.0 feet)
Wind Dissemination
  • Not wind disseminated
Moisture Regime
  • Aquatic
  • Semi-aquatic
  • Seasonally saturated
Chlorophyll
  • Present

Stem Cross Section
  • Ridged
  • Square
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
  • Stoloniferous
  • Tap Root

US State
  • Massachusetts
  • Maine
  • Michigan
  • New Hampshire
  • New Jersey
  • New York
  • Ohio
  • Pennsylvania
  • Rhode Island
  • California
  • Idaho
  • Oregon
  • Washington
Canadian Province or Territory
  • British Columbia
  • Ontario

  • Aquatic and Riparian Plants of the West, 2003 (ISBN# 1-879906-59-7) See page: 237
  • California Growers Weed Identification Handbook, 1968 - 1998 University of California Publication # 4030-1, See page: 120
  • Garden Weeds of Southern California, 1981, See page: 71
  • Weeds of California, 1970, State of California Publications and Documents. See page: 312
  • Weeds of California and other Western States, 2007 (ISBN 13: 978-1-879906-69-3) See Page: 908
  • 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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