Identification and Reproduction

Identification: 

• Common tansy is a perennial in the daisy family (Asteraceae).
• It grows upright from purplish-red stems.
• Leaves are alternate, deeply divided, toothed and dark green.

• Flowers are bright yellow with flat tops, appearing like buttons. Flowers form in clusters of 20-30 on each plant stalk. 

Reproduction:

• Common tansy is a prolific seed producer. Seeds can be spread by birds, animals, and people.
• It can also spread through rhizomes.

Habitat & Ecology

• Common tansy is present throughout southern B.C. and the Fraser Valley. 
• It can grow in disturbed sites and likes sunny, well-drained areas.
• Often found on pastures and roadsides.

Impacts

Social: 

• Plants contain a toxic alkaloid that is toxic to both humans and livestock. 
• Common tansy if consumed by dairy cattle has been found to produce an unpleasant milk. 

Ecological:

Dense patches of common tansy will displace native vegetation. 

Management

Mechanical/Manual Control:

• Mowing has the potential to reduce seed production, but will require repetition. It is most successful before flowering in July. 
• Hand cutting the seed heads is also effective. 
• In small patches hand pulling may be appropriate. 
• Be sure to wear gloves and other protective clothing to prevent skin irritation. 

For alternative planting options to common tansy download the ISCBC's Grow Me Instead brochure (pg. 17 and 18).

Resources

Download A Guide to Weeds in British Columbia for Common Tansy here.

Header photo (Strecosa). 

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