COMMON TANSY — Tanacetum vulgare L.

Asteraceae — (Sunflower family)

The leaves are deep green and feathery, growing from seeds or from existing perennial roots.  Woody stems are about 3 ft tall in Wyoming.  The flowers are flat, yellow and button like, growing in umbrella shaped clusters at the tops of the stems.  The “flower” dries brown and sheds the seeds.  This plant is of no use to animals but is harvested as a medicinal by some. 

The following is courtesy of Weeds of the West:

Common Tansy is a native of Europe and came to the U.S. as an ornamental and for medicinal purposes. It is an aromatic perennial and is generally found along roadsides, waste areas, stream banks and in pastures throughout most of the U.S. and Canada.

It reproduces from seeds and rootstalks. Leaves are alternate, deeply divided into numerous, narrow toothed segments. Yellow flower heads, ¼ to ½ inch across, are numerous in flat-topped dense clusters. Seeds are yellowish-brown with short 5-toothed crowns.

Common tansy is sometimes mistaken for Tansy ragwort. Non-Standard name: garden tansy.

Growth Habit: Perennial, bushy upright, stems are from 1 ½ to 6 feet tall.

Leaves: Divided into individual leaflets, serrated on the margins.

Stem: Many stems, often purplish-red in color.

Flower: Flower heads contain button-like flowers without petals ¼ to ½ inch across and growing in dense, flat topped clusters.

Roots: Rootstalks.

Seeds: Yellowish-brown with short, 5-toothed crowns.
(Courtesy of Weeds of the West)

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