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Hairy willow herb

Hairy willow herb (Epilobium hirsutum)

Semi-aquatic perennial herb that grows 3-6’ tall, with fine, soft hairs covering the entire plant. Stems are tall and branching. Grows in open, moist habitats.

Overview

Regulated areas of hairy willow herb
Hairy willow herb is Prohibited (Red counties)/Restricted (Orange counties)

Other names for this plant include:

  • Common names: codlins and cream, European fireweed, great willowherb

Ecological threat:

  • It forms dense, monotypic stands that can be found in open riparian areas along streams, ditch banks, wetlands and moist waste places.
  • Can be found in undisturbed natural areas due to the seed easily spreading by wind, water or transported by humans or animals.

Classification in Wisconsin: Prohibited/Restricted (Restricted in Brown, Calumet, Door, Kenosha, Kewaunee, and Manitowoc counties; Prohibited elsewhere)

Species Assessment Groups (SAG) were assembled to recommend a legal classification for each species considered for NR 40. The recommendation for hairy willow herb was based upon this literature review developed by the department.

Identification

Leaves: Opposite and stalkless, with sharply toothed edges and a prominent central vein. They are oblong-lance shaped, 2-5" long and widest below the mid-point.

Flowers: Numerous, 0.75" wide, rose-colored flowers arise from the leaf axils. Each flower has 4 notched petals, 4 sepals and a white four-lobed stigma rising above the bloom. Blooms mid-late summer.

Fruits & seeds: Fruit is a 2-3" long, tubular capsule, containing many small, oblong, flattened seeds, each with a tuft of silky white hairs that aids in wind dispersal.

Roots: Large root system with branching rhizomes that grow up to 2' long.

Similar species: Native fireweed (Epilobium angustifolium) can be distinguished from hairy willow herb by its alternate leaves and multiple stalked flowers arranged in a terminal raceme.

Distribution

Known county distribution of hairy willow herb
Counties in WI where hairy willow herb has been reported (as of July 2011). Both vouchered and unvouchered reports included.

Do you have hairy willow herb in your county but it isn't shaded on the map? Send us a report.

Control

Mechanical: Hand pull or dig, removing all plant parts. Mowing within 3 weeks of flowering can effectively eliminate annual seed production. Avoid control measures once seed has matured.

Chemical: Foliar spray a broad-spectrum herbicide that is able to translocate into roots and rhizomes, such as glyphosate or imazapyr.

Photos

View hairy willow herb pictures in our photo gallery!

Resources

Sources for content:

  • Czarapata, Elizabeth; Invasive Plants of the Upper Midwest: an illustrated guide to their identification and control. University of Wisconsin Press. 2005. Pg. 135
  • Invasive Plant Atlas of New England: Hairy willow-herb [exit DNR].

Links for More Information

Last revised: Monday December 11 2017