Scientific NameTanacetum vulgare
Other Common Names:
Synonyms (former Scientific Names):
Seedlings are comprised of 2 cotyledons 2.3-4 mm long by 1-2 mm wide that are ovate in shape. Common tansy spreads by both seed and it's creeping root. Woody and aromatic the hairless stems can reach 1.8 m in height and are frequently purplish red near the base.
Doubly divided into narrow toothed segments leaves are 5-25 cm long and 4-8 cm wide. They bear several small glands lending this plant its strong odor.
Woody purplish red stems, numerous button-shaped flower heads and aromatic crushed leaves. This plant is an alternate host for chrysanthemum stunt virus.
Flower Seed Head
20-200 yellow flower heads make up the flat topped clusters. Flower heads are 5-10 mm wide and are shaped like buttons, ray florets are not present.
Each of the numerous disk florets yield a single seeded achene. Each achene in turn contains a 1.5 mm long gray to tan oblong seed with longitudinal ribs. A short 5-lobed crown serves as a pappus to each seed. Best germination rates of the over 50,000 seeds produced by each plant are in the top 2 cm of soil.
Throughout Canada and the United States common tansy can be troublesome in pastures because livestock generally find it to be unpalatable. Not usually a concern in cultivated crops because it is easily controlled with cultivation.