hairy willow-herb

Epilobium hirsutum

   

Family: Onagraceae

Weed Class: B

Year Listed: 2004

Native to: Africa, Asia and Europe

Toxic: not known to be

Other Legal Listings: WA Quarantine list, WAC 16-750

additional photos

 

   

Why is it a noxious weed?

Hairy willow-herb is a tall, attractive plant capable of escaping cultivation to form monotypic stands in natural wetland areas. Aggressive and dense growth can crowd out native or beneficial species.

How would I identify it?

General Description: Hairy willow-herb is a semi-aquatic, softly-hairy herb that ranges in height from 3 - 6 feet tall.

Flower Description: The showy rose-purple flowers extend from leaf axils near the top of the plant. Flowers are approximately ¾ inch across. Each flower has four sepals, four notched petals and eight stamens. Blooms occur in July and August.

Leaf Description: The leaf arrangement is mostly opposite, and the toothed leaves are lanceolate shaped (much longer than wide, and widest below the middle).

Stem Description: Stems are upright, branched more near the top and covered in hairs.

Fruit/Seed Description: The seeds are in long narrow capsules. Seeds have a tuft of white hairs attached.

May be confused with:

How does it reproduce?

It spreads by seeds and by rhizomes and adapts to its growing conditions. Axillary buds, found at the base of the stem, produce stolons. These stolons develop adventitious roots which pull the stolons into the ground where they develop into rhizomes.
 

Where does it grow?

It is found in a wide range of moist soils, including wetlands, ditch and stream banks, low fields, pastures and meadows. Please click here to see a county level distribution map of hairy willow-herb in Washington.
 

How do I control it?

Mechanical Control

Small infestations may be hand dug, but care must be taken to remove as many rhizome fragments as possible. Sites must be checked for re-growth from missed root fragments. Mowing may be an option to prevent seed production but will not kill the plant.

Herbicide Control

Please refer to the PNW Weed Management Handbook, or contact your county noxious weed coordinator.


 

For more information

 
Department of Ecology's Integrated Pest Management Profile of Hairy willow-herb.
WSDA Report on testing control methods of (Epilobium hirstum).
See our postcard for early detection information about hairy willowherb.
See our Written Findings for more information about hairy willow-herb (Epilobium hirsutum).

Additional Photos


 
 

 


Hairy willow-herb flower

 


Hairy willow-herb growth with flowers

 


Hairy willow-herb seeds with hairs

    

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