Weed Information: Epilobium brachycarpum (willowweed, panicle)
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Epilobium brachycarpum (willowweed, panicle)

Family: Onagraceae

Description

In the seedling stage, note the deep red-purple color on the backs of the leaves and cotyledons. The leaf margins have very small, widely spaced teeth. Although the plant is an annual, the lower stem often appears woody and the epidermis bark-like, dry and peeling. This is typical of many members of this family. A highly variable species with several varieties. Common on road shoulders. Flowering in late summer and fall.

Characteristics

Flower Color
  • Red (or pink)
  • Blue-purple
  • Purple
  • Red-purple
Inflorescence Type (How the flowers are arranged on the plant)
  • Panicle
Number of Petals
  • 4 petals
Petal Separation
  • Completely free to base
  • United at base only (<25% length)
Petal Tip
  • Bilobed
Flower Symmetry
  • Flowers regular
Flower Length (Head length in the Asteraceae)
  • 5 mm (.20 inch)
  • 6 mm (.24 inch)
  • 7 mm (.28 inch)
  • 8 mm (.32 inch)
  • 9 mm (.36 inch)
Flower Width (Head width in the Asteraceae)
  • 6 mm (.24 inch)
  • 7 mm (.28 inch)
  • 8 mm (.32 inch)
  • 9 mm (.36 inch)
  • 1.0 cm (.40 inch)
  • 1.5 cm (.60 inch)
Number of Sepals
  • 4 sepals
Sepal Separation
  • Completely free to base
Sepal Tip
  • Pointed
Flower Sex
  • Bisexual (perfect)
Number of Styles
  • 1 style
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
  • 4 carpels
Ovary Position
  • Inferior (epigynous)
Fruit Type
  • Capsule, > 3-celled
Fruit Length at Maturity
  • 2.0 cm (.80 inch)
  • 2.5 cm (1.0 inch)
  • 3.0 cm (1.2 inches)
Fruit Width at Maturity
  • 2 mm (.08 inch)
  • 3 mm (.12 inch)
  • 4 mm (.16 inch)
Burs
  • Fruit or seed NOT bur-like

Leaf Arrangement
  • Alternate
  • Opposite
  • Opposite below, alternate above
  • Fascicled
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 - 5 mm (.04 - .20 inch)
  • 5 - 10 mm (.20 - .40 inch)
Leaf Shape (simple leaves only)
  • Lanceolate
  • Linear or filiform
Leaf or Leaflet Margin
  • Dentate
  • Entire
Leaf or Leaflet Blade Base
  • Acute (cuneate)
Leaf or Leaflet Tip
  • Acute
  • Rounded (obtuse)
Leaf or Leaflet Blade Surface
  • Glabrous (NO hairs)
  • Glandular
  • Puberulent
Succulence
  • Not succulent

Milky Juice
  • Juice NOT milky (watery)
Woodiness
  • Herbaceous
  • Semi-woody
Spines or Thorns
  • Spines or Thorns ABSENT
Aromatic (vegetative structures)
  • Not aromatic
Life Cycle
  • Annual
Growth Habit (while flowering)
  • Erect, columnar (narrow)
  • Erect, spherical (bushy)
Plant Height at Maturity
  • 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)
Wind Dissemination
  • Fruit, seed, or spore wind borne
  • Entire plant mobilized (tumbleweeds)
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
  • Kentucky
  • Wisconsin
  • Arizona
  • California
  • Colorado
  • Idaho
  • Minnesota
  • Montana
  • North Dakota
  • New Mexico
  • Nevada
  • Oregon
  • South Dakota
  • Utah
  • Washington
  • Wyoming
Canadian Province or Territory
  • British Columbia
  • Ontario
  • Quebec
  • Alberta
  • Manitoba
  • Saskatchewan

  • California Growers Weed Identification Handbook, 1968 - 1998 University of California Publication # 4030-1, See page: 18
  • Gilkey`s Weeds of the Pacific Northwest, 1980 (ISBN 0-88246-039-0) See page: 199
  • Weeds of California, 1970, State of California Publications and Documents. See page: 313, 314
  • Weeds of California and other Western States, 2007 (ISBN 13: 978-1-879906-69-3) See Page: 955
  • Weeds of the West, 2000 (ISBN 0941570-13-4) See page: 394
  • 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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