(Tanacetum Vulgare)
By Sarah Busdon
Common tansy is found in nearly every state throughout the United States.
Tansy was introduced from Europe in the 1600s and, because of its medicinal uses and popularity as an ornamental planting, it was planted and cultivated in the yards and gardens of early settlers. It is currently designated as a noxious weed in five states.
Common Tansy is an invasive plant because, once established, it’s aggressive in forming dense stands and displaces desirable forbs and grasses, impacting wildlife habitat, and is often found along with other noxious weeds like Canada thistle and knapweed. It is commonly located in recently disturbed sites, including along roadsides, riverbanks, stream banks, pastures and irrigation ditches.
Common tansy is also known as garden tansy and golden buttons. It’s an aromatic perennial, with rhizomes, reaching 1 to 5 feet tall, with fern-like foliage in the aster family. Flower heads are numerous, distinguishable by clusters of small, button-like yellow flowers that lack ray petals. Leaves are alternate and pinnately compound and irregularly lobed with leaves becoming smaller toward the tip of the stalk. Leaves and stems have a strong smell if crushed.
The plants reproduce by seeds and rhizomes. Its flower heads are capable of holding seeds through the fall, when they may be dislodged from the dried flower head and spread by wind, birds, animals, vehicles, and water. More established plants are also capable of spreading by creeping rhizomes, which form dense patches.
If you have this plant near or around your home, there are ways you can treat it. For more information contact your local Extension office.
Sarah Busdon is an administrative assistant with University of Idaho’s Blaine County Extension office. For more information, visit www.extension.uidaho.edu/blaine or call (208) 788-5585.