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Hairy Willowherb Epilobium hirsutum

Phonetic Spelling
ep-ih-LOW-bee-um her-SOO-tum
Description

Hairywillow herb is a semi-aquatic annual or perennial in the Onagraceae family native to North Africa and Eurasia.  The soft wooly leaves and stems are the reason for the species name hirsutum which means hairy in Latin. This plant reaches a mature height of 6 feet tall.  

While they are more common in cool regions they occasionally occur as a cool-season weed in warmer areas.  Hairywillow herb grows in moist soils and is often found growing in full sun in wetlands, low areas, in ditches, along roadsides, and along stream beds.  Often found growing with the invasive weed purple loosestrife,  it reproduces through rhizomes or by wind dispersed seed.

Seedlings are small and slow to establish, but once established can be challenging to manage. This weed is becoming more prevalent in container nurseries, likely spreading in contaminated nursery crops. Inspect liners to prevent introduction. Prevent plants from going to seed. Willowherbs are not well managed by herbicides currently labeled for use. Herbicide efficacy rankings for this species are based on limited experimental data.  

Insects, Diseases, and Other Plant Problems: This plant is weedy, can spread aggressively, and has been marked as invasive in some regions including northern parts of the USA.  Do not compost, dispose of this plant in the garbage.  

See this plant in the following landscape:
Cultivars / Varieties:
Tags:
#weeds#pink flowers#weedy#wetlands#stream banks#ditches#agressive#wind dispersed seeds#hairy leaves#annual weed#cool season weed#hairy stems#perennial weeds#wet soils tolerant#roadside#meadows#aquatic#wet sites#semi-aquatic
 
Cultivars / Varieties:
Tags:
#weeds#pink flowers#weedy#wetlands#stream banks#ditches#agressive#wind dispersed seeds#hairy leaves#annual weed#cool season weed#hairy stems#perennial weeds#wet soils tolerant#roadside#meadows#aquatic#wet sites#semi-aquatic
  • Attributes:
    Genus:
    Epilobium
    Species:
    hirsutum
    Family:
    Onagraceae
    Life Cycle:
    Annual
    Perennial
    Country Or Region Of Origin:
    Temp. Eurasia to Africa
  • Whole Plant Traits:
    Plant Type:
    Annual
    Perennial
    Weed
    Habit/Form:
    Erect
    Growth Rate:
    Slow
    Maintenance:
    High
  • Cultural Conditions:
    Light:
    Full sun (6 or more hours of direct sunlight a day)
    Soil Drainage:
    Moist
    Occasional Flooding
    Occasionally Wet
  • Fruit:
    Fruit Length:
    1-3 inches
    Fruit Description:
    Dehiscent hairy thin seed pods 1 to 3 inches long. Seeds have white tufts of hair that aid in their dispersal by wind.
  • Flowers:
    Flower Color:
    Pink
    Flower Bloom Time:
    Winter
    Flower Shape:
    Saucer
    Flower Petals:
    4-5 petals/rays
    Flower Size:
    < 1 inch
    Flower Description:
    The flowers are saucer shaped rose pink with white centers, resembling primrose blooms. 3/4" across, four petals with a notch at the top, four sepals, and eight stamens. They appear at the top of the plant in leaf axils. Long seed pods split open to release many wind-dispersed seeds.
  • Leaves:
    Leaf Color:
    Green
    Leaf Type:
    Simple
    Leaf Arrangement:
    Opposite
    Leaf Shape:
    Lanceolate
    Leaf Margin:
    Dentate
    Hairs Present:
    Yes
    Leaf Description:
    Mostly opposite densely hairy toothed lanceolate leaves with no petiole, they attach directly to the stem. The leaves are deeply veined.
  • Stem:
    Stem Color:
    Green
    Stem Is Aromatic:
    No
    Stem Surface:
    Hairy (pubescent)
    Stem Description:
    Stems are erect, branched, very hairy.
  • Landscape:
    Resistance To Challenges:
    Wet Soil
    Problems:
    Weedy