Mugwort

Mugwort (Artemisia vulgaris), also called chrysanthemum weed, is an upright perennial with very distinctive alternate, deeply dissected (lobed) leaves that closely resemble those of garden chrysanthemums. The upper leaf surface is bright green and smooth while the lower surface is pale green and densely woolly-hairy, giving leaves a silvery underside. The foliage emits a strong sage-like odor when crushed, a reliable confirming trait. Plants grow erect from a vigorous, persistent rhizome system; this combination of chrysanthemum-like dissected leaves, white-woolly leaf undersides, and aromatic foliage distinguishes mugwort from other broadleaf weeds.

Mugwort forms dense, expanding patches whose tall, leafy, aromatic shoots overtop and shade out turfgrass, displacing the stand and creating coarse, weedy areas that disrupt turf uniformity; its persistent rhizomes resist cultural removal and mowing, so colonies enlarge year over year, steadily reducing turf density and competing strongly with grass for light, water, and nutrients.

Mugwort is a perennial that spreads primarily by an extensive, strong, persistent system of rhizomes (underground stems); even small rhizome fragments left in the soil can regenerate into new plants, which is why disturbance and tillage spread rather than control it. It also produces seed, but rhizomatous vegetative spread drives most colony expansion. The plant regrows each spring from rhizomes and crowns and forms expanding patches over time.

Mugwort is an aggressive invader of low-maintenance and disturbed turf, roadsides, landscape edges, and neglected areas, and once established its rhizome network makes it extremely difficult to remove. Thin, poorly maintained stands and disturbed soil give it openings to establish, and because rhizome fragments are readily moved by equipment and soil, infestations often originate from contaminated fill or spread along maintained edges.