COMMON TANSY (TANACETUM VULGARE L.)
An aromatic perennial forb with clusters of yellow flowers, growing to 1.5m in height. Bloom period is July to October. Flowers are button-like and yellow, in dense, flat-topped clusters at the top of the plant. Leaves are alternate and fern-like. Seed are yellow-brown with short 5-toothed crowns. Roots are rhizomatous.
Habitat and Ecology
Common tansy is scattered in low- to mid-elevation disturbed sites, including roadsides, stream banks, and disturbed pastures. It prefers sunny habitats with well-drained soil.
This species may be toxic to livestock; it is an undesirable forage plant. It may displace native species. It has been used as a medicinal herb, but can be toxic to people if consumed in large quantities.
The rhizomatous nature of this plant can make it difficult to eradicate. Small root fragments can produce new plants, and cut stems can go to seed. Mechanical methods (mowing and hand cutting) before flowering can be effective in eliminating seed production, but this method will have to be repeated as rootstock will re-grow. New infestations can be prevented by minimizing disturbance, eliminating seed production, and maintaining healthy native plant communities. Fire is not likely to minimize the spread of common tansy, but it can be used to dispose of cut stems and flowers. Herbicides are effective if applied between the flower bud stage and the bloom stage. Consult the BC Ministry of Agriculture, Food and Fisheries Crop Production Guides for recommendations.
Province of British Columbia. 2002. Guide to Weeds in British Columbia.
USDA Fire Effects Information System http://www.feis-crs.org/beta/
Photo reference: Michael Shephard, USDA Forest Service, Bugwood.org