Native Range

Europe, Siberia, and Asia

Appearance

Tansy ragwort is an herbaceous biennial (sometimes a winter annual or short-lived perennial) typically growing 1–3 ft (30– 90 cm) tall. The root system consists of one to several soft, fleshy roots. Leaves are deeply lobed to pinnately toothed, alternate, and 3–8 in (7½–20 cm) long. Stems arise singly or in clumps and branch near the top with multiple flower heads. Flowering occurs from July to September. Flower heads consist of yellow disc (center) and ray (outer) florets. Ray florets (usually 13) resemble petals and grow S–¾ in 8–20 mm long. Seeds are topped by a fine pappus.

Impact

Tansy ragwort displaces native species in natural areas and reduces range and pasture production. All parts of the plant contain pyrrolizidine alkaloids that are responsible for livestock fatalities, contaminating milk production, and the tainting of honey made from tansy ragwort nectar. Many people are also allergic to this weed.

Reference

Szucs, M., J. Littlefield, C.B. Randall, and J.E. Andreas. 2022. Tansy Ragwort (Jacobaea vulgaris): History and Ecology in North America. In: R.L. Winston, Ed. Biological Control of Weeds in North America. North American Invasive Species Management Association, Milwaukee, WI. NAISMA-BCW-2022-21-TANSY RAGWORT-P. https://bugwoodcloud.org/resource/files/25373.pdf

Selected Images

Maps

Invasive Listing Sources

• Alberta Weed Control Act
• California Invasive Plant Council
• California Noxious Weeds
• Colorado Noxious Weeds
• Connecticut Invasive Plant List
• Connecticut Invasive Plant Working Group
• Idaho Noxious Weeds
• Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
• John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
• Massachusetts Invasive Plants Advisory Group List
• Massachusetts Noxious Weeds
• Massachusetts Prohibited Plant List
• Montana Noxious Weeds
• Native Plant Society of Oregon, 2008
• New Invaders of the Northeast and Northcentral
• Oregon Noxious Weeds
• Pacific Northwest Exotic Pest Plant Council, 1998
• Washington Noxious Weeds
• WeedUS - Database of Plants Invading Natural Areas in the United States

References