Common tansy is a fibrous-rooted perennial that spreads from root stalks and seeds. It grows from 18-36 inches high. It has yellow-to-orange button flowers that occur in dense flat-topped clusters. The stems are red-to-brown and become woody towards the base of the plant. The leaves are aromatic and fern-like, with deep alternating lobes.
Tansy has had a long history of uses in the United States; during colonial eras it was actual actively propagated. Historically, it has been used for minor medicinal purposes, a bug deterrent, a funeral decoration, and to pack meats (for alleged anti-fungal and preservative qualities). It’s important to note, though, that this plant also produces toxic alkaloids when consumed by human and animals, if consumed in large quantities. There is some evidence that these alkaloids may be absorbable through the skin, so wear gloves when you are handling tansy.
In Teton County, common tansy has been seen moving along old irrigation ditches, invading moderately wet sites, and establishing in riparian areas.
For help managing infestations,
please call Teton County Weed & Pest District 733-8419.