Herb to Know: Tansy


| June/July 2011



tansy 1

You can grow quaint tansy in your garden easily. Just remember, it's considered toxic today, so don't ingest this herb.

Photo by Rob Cardillo

Common tansy (Tanacetum vulgare) is an upright perennial herb with strongly aromatic, fernlike green leaves whose aroma reminds some people of pine, others of chrysanthemum or camphor. Under favorable conditions, the plant may reach 5 feet tall, but 3 feet is more likely. From July to October, it is decked with flat clusters of 1/4 - to 1/2 -inch mustard-yellow buttons like the centers of daisies. The seed heads persist through the winter; in spring, the tiny seeds drop to the ground and soon germinate to begin a new generation. Common tansy is a native of Europe and Asia. The Puritans brought it to this country in the 17th century, and it is now naturalized throughout much of Canada and the United States.

Common tansy Tanacetum vulgare
• Family: Compositae (Asteraceae)
• Hardy perennial
 
Click here to see a close-up image of tansy. 

Curly or fern-leaf tansy (T. v. var. crispum) is common tansy’s city cousin. Its leaves are longer, broader, more finely cut and down-curving. The plant is denser and more decorative and grows only 2 to 3 feet tall. The flowers are similar to those of the common species, but the plant may not blossom at all where summers are cool. 

Both the English name tansy and the Latin generic name Tanacetum are thought to derive from the Greek athanasia, or immortality. What does tansy have to do with immortality? There are several possible connections. The flowers are long-lasting; the leaves were used to preserve dead bodies (or at least to disguise the smell), and in Greek mythology, Ganymede, a beautiful youth carried up to Olympus by an eagle to become cupbearer of the gods, was made immortal with a drink containing tansy.  

Many people know tansy as a roadside weed, an opportunistic inhabitant of waste places, but herbalists of old considered it a valuable medicinal herb, good for just about any health problem. They recommended it for (among other ailments) worms, hysteria, kidney weakness, fevers, flatulence and gout. Externally, tansy was applied to rashes and to the swelling accompanying a sprain. In Sussex, leaves placed in the shoes were thought to cure ague. Some uses seem contradictory: It was prescribed to bring on menstruation, yet when boiled in beer and drunk or when the bruised leaves were applied to the navel, it was thought to prevent miscarriages. Small doses of the essential oil were used to treat epilepsy, but larger ones could cause seizures or death.

The essential oil is today considered toxic and potentially fatal; it contains thujone, a convulsant and narcotic. It makes sense to avoid any medicinal or culinary concoction containing tansy, especially during pregnancy. Even when used externally, tansy can irritate the skin; the AMA Handbook of Poisonous and Injurious Plants (American Medical Association Press, 1985) lists tansy in a table of plants that cause contact dermatitis.





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