- Tanacetum vulgare
Common tansy (Tanacetum vulgare) is a perennial and considered regionally noxious under the BC Weed Control Act. Common tansy is currently distributed in the following areas: Bulkley-Nechako, Central Kootenay, Columbia-Shuswap, East Kootenay, and North Okanagan Regional Districts, and within Greater Vancouver, Fraser Valley, southeast coast of Vancouver Island, Gulf Islands, Sunshine Coast, and Squamish/Pemberton.
Common tansy has yellow disc flowers that resemble buttons in a flat-topped cluster at the top of the plant. With fern-like leaves, common tansy can grow 0.4–1.5 metres in height at maturity.
Spread mainly through seeds and roots, common tansy can be transported by birds, animals, and on vehicles that have been in infested areas. Seeds can remain viable for up to 25 years; therefore, stopping seed spread is a main concern. Common tansy prefers sunny areas with well-drained soil, and often infests stream banks, pastures, and disturbed sites such as roadsides. Infestations may be toxic to livestock and to humans if large quantities are consumed.
A few native and ornamental alternatives to plant instead of common tansy include: Yarrow; Tall Coneflower; Summer Sunflower; Morden Eldorado Garden Mum; and Flat-top Goldentop. Read more about these alternatives in the Grow Me Instead booklet for BC.