Synonyms: Other names: gold-buttons, curl-leaf tansy Nomenclature: vulgare = common, ordinary Nativity / Invasiveness: noxious weed in Montana
General: aromatic plant, 40-150 cm tall. Growth habit: coarse perennial from stout rhizomes, often in dense colonies. Stems: branching, leafy, mostly hairless.
Leaves: alternate, numerous, 10-20 cm long and nearly half as wide, hairless, stalkless or short-stalked, fern-like, twice pinnately divided into fine segments. Leaves and segments with broadly winged axis and dotted with small pitted glands.
Flowerheads: yellow, with disk florets only, about 5-10 mm wide, numerous, commonly 20-200, in flat-topped, branching clusters. Involucral bracts broad, lance-shaped, with dark edges, in 3 overlapping rows.
Fruits: achenes, glandular-dotted, with pappus a minute, toothed crown, almost obsolete.
Roadsides, fields, and disturbed areas in w. c. and s. parts of MT. Introduced from Europe, escaped from cultivation and well established throughout much of the U.S. and Canada.
Young leaflets of tansy are edible raw or cooked. They can be added in small quantities to salads. The plant is also used as a flavoring, it is a substitute for nutmeg and cinnamon. The flowers have a unique flavor and can be eaten or used as a garnish. A bitter, somewhat lemon-flavored tea is made from the leaves and flowering stems.
Tansy is a commonly grown domestic remedy, useful in treating a wide range of complaints, though it is little used in modern herbalism. Its main value is as a vermifuge to expel intestinal worms and, to a lesser degree, to help stimulate menstrual bleeding. Tansy should be used with caution, however, it is possibly unsafe for internal use, especially for pregnant women. The essential oil in the leaves is toxic and as little as ½ oz can kill an adult. The leaves and flowering tops are antispasmodic, bitter, and have agents that destroy and expel worms from the intestines, that relieve and remove gas from the digestive system, that promote or assist the flow of menstrual fluid, and are stimulant and tonic. An infusion of the leaves or whole plant is used to treat menstrual irregularities and to expel worms from the intestines, especially for children. It is also valuable in treating hysteria, kidney weaknesses, stomach problems, fevers and also to promote the flow of menstrual fluid. In larger doses the plant can procure an abortion, though these doses can be poisonous. Externally, tansy is used as a poultice on swellings and some eruptive skin diseases. It is also used externally to kill lice, fleas and scabies, though even external use of the plant carries the risk of toxicity. The plant is harvested as it is coming into flower and is dried for later use. The seeds are used to expel worms from the intestines.
A green dye is obtained from the young shoots. The leaves and flowers can also be used and a yellow can also be obtained. The plant is used as a strewing herb in cellars, churches etc in order to repel insects. Both the growing and the dried plant are said to repel flies, ants and fleas, especially if they are mixed with elder leaves (Sambucus spp.). The leaves and the flowering shoots contain 0.15% of an essential oil that contains camphor, borneol and thujone. Both the leaves and the oil and they have been used to kill fleas and lice. Thujone is an effective insecticide, but it is highly toxic to mammals when taken in excess. The plant is a good addition to the compost heap, being valued for its mineral content.
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