Name: Mugwort or Common Wormwood (Artemisia vulgaris)
Origin: Mugwort is native to Europe and Asia, where it was utilized as a medicinal and culinary herb. It was introduced to North America through ship ballast and continues to spread across the continent via nursery stock, turf grass and roadways.
NYS Presence: Widespread throughout the state and often found in ditches, roadsides, pastures and other disturbed areas.
Species Profile: Mugwort is a perennial that flowers in late summer to early fall. Its alternating dark green leaves are smooth on top and have silvery-white hairs underneath. When the foliage is crushed it is known to release a pungent odor. One plant can produce as much as 200,000 seeds which are roughly 1mm in diameter and are spread by the wind and easily moved around on tires, mowers and construction equipment. As a result, Mugwort can be found along miles of roadside.
Although seed dispersal plays a large role in the spread of this invasive weed, its root system is also a culprit in increase this weed’s introduction to new sites. Nursery stock including ornamental plants, turf grass, and orchard stock are easily contaminated by these root fragments and carried into new places. Mugwort’s rhizomatous roots – an extensive and dense underground network — and the abundance of seeds make this species very hard to control.
Mugwort has displaced many native plants, especially those that thrive in sunny, open habitat. Cleaning equipment, using clean fill (e.g., at construction or landscaping sites), and removing and disposing of any new infestations of Mugwort are some of the ways to reduce the spread of this plant.
Resources:
Barney, J.N. and A. DiTommaso. 2003. The biology of Canadian weeds. 118. Artemisia vulgaris L. Canadian Journal of Plant Science 83:205-215.
http://www.nyis.info/index.php?action=invasive_detail&id=63
http://www.nrcresearchpress.com/doi/pdf/10.4141/P01-098
Featured image, mugwort growing along a forest edge, photo by Ansel Oommen, Bugwood.org
New York State Parks and Historic Sites Blog 
I have been trying to control mugwort on my property without much success. I am surrounded on 3 sides by forest. Mostly oak & other hardwoods. My question is can it & will it spread into the woods killing off the native understory plants? Also garlic mustard has spread that way & I have pulled what I was able to.