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Wormwood

(Artemisia absinthium)

Photo of wormwood
Photo credit: Chris Evans, Illinois Wildlife Action Plan, Bugwood.org

A fragrant perennial herbaceous plant with a woody stem. The fragrance resembles that of garden sage.

Overview

Other names for this plant include:
  • Common names: artemisia, absinth sage, absinth wormwood, absinth sagewort, common sagewort, absinthe mugwort, absinthium
  • Scientific names: Artemisia absinthium var. absinthium; Artemisia absinthium var. insipida
Ecological threat:
  • Invades coniferous and hardwood forests, prairies, meadows, grasslands, fields, and disturbed areas.
  • Viable seeds have been found in undisturbed grassland prairies.
  • Plants are prolific seed producers.
  • Naturalized throughout much of the United States.
  • Alters the flavor of milk when cows consume the plant.
  • Chemical compounds may inhibit the growth of some surrounding plant species while stimulating the growth of others.
Overview map of wormwood classification in WI
Restricted (orange) counties

Classification in Wisconsin: Restricted

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

Identification

Leaves & stems: Leaves are light green- greyish in color, and covered in fine, silky white hairs. Deeply pinnately divided with round lobes/edges. The fragrance is similar to garden sage. Stems are somewhat woody.

Flowers: Small tubular flowers borne on dangling and dropping stalks form yellow clusters.

Fruits & seeds: Light brown seeds are shaped like sunflowers seeds, broader at the base and more narrow at the tip.

Roots: Plants have central taproot as well as long-branching lateral roots. Plants are mildly rhizomatous.

Similar species: Wormwood resembles many other species in the genus Artemisia, some of which are of special concern and others are introduced non-natives:

Artemisia ludoviciana [native] – Leaves are lance-shaped and undivided (with few to no lobes). Artemisia serrata [native] – Lance-shaped slender leaves have toothed edges. Artemisia frigida [native, special concern]. Artemisia dracunculus [native, special concern] – Flower heads are erect, not nodding like the invasive A. absinthium.

Visit the Wisconsin State Herbarium link under the resources tab for more information on identification.

Control

Mechanical:
  • Dig up individual plants. For larger populations, mow as close to the ground as possible. Monitor for re-sprouts.
  • Cover the infestation with black landscape fabric/plastic in early spring, when leaves emerge. Keep covered for a minimum of one growing season.
  • With sufficient fuel loads, consecutive prescribed burns are also a successful control option.
Chemical:
  • Picloram, dicamba, 2,4-D, and glyphosate are all effective herbicides. Follow the recommended label rates.

Photos

View wormwood pictures in our photo gallery!

Resources

Sources for content:
  • Carey, Jennifer H. 1994. Artemisia absinthium. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). [2013, August 12].
  • University of Wisconsin - Stevens Point, Robert W. Freckmann Herbarium
  • Center for Invasive Species and Ecosystem Management; invasive.org
Links for more information: