Absinth Wormwood
Artemisia absinthium
Keys to Identification
Family: Sunflower family 
Other Names: American wormwood, common wormwood, mugwort, madderwort and wormwood sage
USDA Code: ARAB3
Legal Status: Colorado Noxious Weed List B Identification
Identification
Lifecycle: Perennial forb or herb
Growth form: 3-5 ft tall. Woody at base; regrows from crown each spring
Flower: Small, yellow, inconspicuous, numerous ⅛ in wide. Late July - August
Seeds/Fruit: One seeded fruit, 1/16 in long, smooth, flattened and light gray-brown in color
Leaves: Divided into deeply lobed leaflets, light green to olive green color, 2-5 in long
Stems: 20 or more stems grow from woody crown. Covered with fine silky hairs
Roots: Taproot to 2 in diameter with shallow lateral branches up to 6 ft long
Impacts
Agricultural: Reduces available forage, taints milk. Strong medicinal odor.
Ecological: May release allelopathic substances
Human: Used to produce Absinth, a potent alcohol based drink
Habitat and Distribution
General requirements: Variable growing sites
Distribution: Found in north central Colorado. 5,000-7,000 ft elevation
Historical: Introduced from Europe in 1841
Biology/Ecology
Mode of reproduction: Seed, small root fragments Seed bank: 3-4 years
Dispersal: wind, animals, human
Control
Biological: None
Cultural: Invades overgrazed or disturbed areas where there is little competition from other plant species. Management should include proper grazing and rotational grazing techniques that maintain rangelands and prevent invasion of the plant. Disturbed areas should be re-seeded with desirable species to prevent spread
Mechanical: Tillage can prevent establishment of absinth wormwood in crop production areas but root fragments may be dragged and resprout
Mowing - may prevent seed production if mowed several times throughout the growing season, but mowing may be difficult in fence rows or rocky areas
Burning - may not be an effective control method for absinth wormwood as infestations are not reduced and may increase
Chemical: Several herbicides are available for absinth wormwood control. These herbicides can successfully control absinth wormwood if applied when the plant is at least 12 in tall and in the active growing stage.
References
- Lym, R. G., C. G. Messersmith, and A. G. Dexter. 1995. Absinth wormwood control. North Dakota State Univ. Ext. Ser. Circ. W-838. Fargo , ND .
- Species account from USDA Forest Service Fire Effects Information System (FEIS)