Common Tansy (Tanacetum vulgare)

Status:

Listed Noxious Weed In Montana

History:

First Montana Specimen Collected 1

County:

Missoula

Year:

1936

Habitat:

Growth Habit:

Perennial, erect, bushy, to 6 feet tall

Leaves:

Dark green, alternate, deeply divided into numerous narrow, toothed leaflets (fern-like).

Stem:

Often purplish-red in color.

Flower:

Yellow, button-like, without petals, ½ inch across in flat topped dense clusters.

Roots:

Reproduces from roots.

Seeds:

Yellowish brown with short 5 toothed crown.

Other Notes:

"This perennial plant spreads via an extensive, spreading root system and profuse seed production. It especially favors the disturbed soils along ditch banks, where the water quickly spreads the seeds for miles downstream. Common Tansy is now widespread from coast-to-coast across most northern states and Canadian provinces. Despite extensive infestations along ditches, creeks, and roads, the plant is not yet listed as a noxious weed in many places. Most alarming, you can still buy the seed and grow more!

Common tansy is rich in volatile oils. The aromatic fresh young leaves and flowers may be used as a substitute for sage in cooking. The main volatile oil is thujone, a potent and bitter chemical often used medicinally as a wash to treat roundworm, or internally to expel worms and cause abortions. Excess consumption of thujone for medicinal purposes has caused convulsions and death. It should not be used without medical supervision. The volatile oil can be distilled from the plants and marketed." (Elpel)