Epilobium hirsutum
Common Name(s):
- Phonetic Spelling
- ep-ih-LOW-bee-um her-SOO-tum
- Description
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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:
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Attributes:
- Genus:
- Epilobium
- Species:
- hirsutum
- Family:
- Onagraceae
- Life Cycle:
- Annual
- Perennial
- Country Or Region Of Origin:
- Temp. Eurasia to Africa
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Whole Plant Traits:
- Plant Type:
- Annual
- Perennial
- Weed
- Habit/Form:
- Erect
- Growth Rate:
- Slow
- Maintenance:
- High
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Cultural Conditions:
- Light:
- Full sun (6 or more hours of direct sunlight a day)
- Soil Drainage:
- Moist
- Occasional Flooding
- Occasionally Wet
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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.
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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.
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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.
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Stem:
- Stem Color:
- Green
- Stem Is Aromatic:
- No
- Stem Surface:
- Hairy (pubescent)
- Stem Description:
- Stems are erect, branched, very hairy.
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Landscape:
- Resistance To Challenges:
- Wet Soil
- Problems:
- Weedy