Common Tansy is an introduced invasive erect perennial forb, growing from 1-1/2 to 3 feet high in sun and up to 5 feet in shade. The stout stems branch near the top, are green with some reddish tints, ridged, and usually smooth but may have some sparse hair.
The leaves are alternate and create a fern-like appearance. They are somewhat oblong to ovate in overall shape and pinnately lobed into 4 to 10 pairs of lance shaped primary lobes. These primary lobes are usually pinnate themselves, with margins that have coarse teeth. The primary lobes begin right where the leaf joins the stem with the lowest pair often looking like large stipules. The larger lower leaves can be 8+ inches long and 1/3 as wide. Leaves become progressively smaller toward the top of the stem. Leaf surfaces may be with or without sparse hair but are gland-dotted and strongly aromatic when crushed, an odor resembling camphor.
The floral array is a grouping of flat-topped stalked arrays (corymbiform) with flower heads numbering 20 to 200+. There are small leaf-like bracts at the base of each array.
Flowers: Each flower is up to 1/3 inch (10mm) wide, hemispheric base with a depressed top. Although a Composite, there are not any ray florets but instead 2 types of disc florets, all of which have yellow tube shaped corollas. There is an outer ring of about 20 florets that are pistillate only and fertile. These open first. The inner group number 60 to several hundred. These are bisexual and fertile with 4 to 5 lobes on the corolla, 5 stamens surrounding a single style. The whole center is flat - like a button - hence the alternate common name of 'golden buttons'. The outside of the flower head has several series of ovate phyllaries, unequal in size, with pointed tips and margins that are thinner and lighter colored than the centers. These persist onto the seed head.
Seed: Fertile flowers produce a dry 4 or 5 angled 1 to 2 mm long cypsela that is gland dotted and has a 5-toothed crown of scales instead of hair for pappus. These are wind dispersed or one may stick to fur or clothing.
Habitat: Tansy grows from a rhizomatous root system which spread the plant vegetatively creating large colonies. It takes root in disturbed areas, roadsides and areas near gardens from which it has escaped. When the area is cultivated, small root sections remaining can still form new plants. Successive cuttings will weaken the root system and eventually kill it, or if you don't want to use herbicide, hot brine or Caustic soda used to do the job in older days. It needs at least partial sun and soils with moist to slightly dry moisture.
Names: The alternate name of Golden-buttons is a reference to the yellow flat-topped flower head. The genus Tanacetum according to Stern (Ref. #37a) is from the Medieval Latin tanazita, a word still used in some European areas. This name may have been derived from the Greek athanasia, for 'immortality'. In the olden days Tansy was a medicinal specific for intestinal worms and was used in Europe and parts of New England in the funeral winding sheets to discourage worms. The species vulgare means 'common'. The author name for the plant classification, 'L.' is for Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.
Comparisons: There are 4 species of Tanacetum in North America, 2 of which are in Minnesota and that one, Fever Few, T. parthenium, has ray flowers with white corollas in addition to the central disc florets.
Above: The upper stem section with the floral array. Drawing courtesy of Kurt Stüber's Online Library. Note the seed shape.
Below: Flowers are of 2 types of disc florets, both fertile - with the outer band of about 20 pistillate only. These open first. the disc is flat like a button.
Below: 1st photo - The phyllaries of the flower head are in several series, ovate, unequal in size, lighter colored margins. 2nd photo - Above the smallest leaves of the stem (left and bottom in photo) , appear some linear small bracts (upper right) at the base of each array.
Below: Leaves are fern-like with each leaf (1st photo) having 4 to 10 pairs of lance shaped lobes. These lobes (2nd photo) are further divided into segments which have coarse teeth; the dotted glands can also be seen in the 2nd photo.
Below: 1st photo - The floral array is a number of stalked flat-topped arrays at the tops of the stems. Flower heads can number 20 to 200+. 2nd photo - Stems are stout, usually smooth, with reddish tints and ridges
Below: The small ribbed 1 to 2 mm long cypselae.
Notes: Even though Tansy was considered an invasive in Eloise Butler's day, she still brought it into the Garden on Oct. 21, 1910 when she transplanted some plants from 21st Street and Cedar Avenue in Minneapolis. All plants needed their day in her opinion. She planted it next to the Creeping Charlie. It was still maintained in the Garden until the 1990s after which it disappeared. However, seeds spread and it may reappear from time to time. Tansy in Minnesota is listed by the Department of Natural Resources as a non-native terrestial invasive plant.
Eloise liked the plant and the reason for planting it, along with several other aggressive plants was to contain Creeping Charley. She wrote: "Various other rampant, naturalized plants, with pleasing foliage or flowers . . . have been planted around him, which, together with the native goldenrods, will tussle with one another for possession of the field. We shall watch the scrimmage with somewhat, we fear, of the Irish delight in a shindy. Last November Tansy also was planted among the contestants. Every root has grown and blossomed, and it bids fair to spread and hold its own with odds in its favor. Tansy is found on the sites of burned down or abandoned houses in the country and is associated with days long past. The finely curt leaves have a pungent odor and the flower disks, bright and golden as sunlight are fine for large bouquets." Published Sept. 24, 1911, Minneapolis Sunday Tribune. Entire article.
There are two species of Tanacetum found in Minnesota, T. vulgare and T. parthenium, Fever Few, which is also introduced and invasive. Tansy is much more widespread, found in over half the counties of the state, with most exceptions in the southern half. In North America it is found throughout except for 5 states near the Gulf Coast and two northern Canadian Provinces.
Uses: Tansy has seen both practical and medicinal use and for that reason, it was originally brought to North America. From a practical standpoint, the oil distilled from the plant makes a good mosquito dope when mixed with oil of Fleabane and Pennyroyal and then diluted with alcohol. Gerard (Ref. #6a) wrote in his Herball in 1597 "In the spring time are made with the leaves hereof newly sproong up, and with egs, cakes or tansies, which be pleasant in taste, and good for the stomacke. For if any bad humors cleave thereunto, it doth perfectly concoct them, and scowre them downwards. The roote preserved with honie or sugar, is an especiall thing against the gowt, if everie day for a certaine space, a reasonable quantitie thereof be eaten fasting. The seede of Tansie is a singular and approoved medicine against wormes, for in what sort soever it be taken, it killeth and driveth them foorth." He goes on to say that "Also being drunke with wine, it is good against the paine of the bladder, and when a man cannot pisse but by drops."
Culpepper (Ref. #4b) writing in The English Physician 75 years later echoes some of the thoughts of Gerard about worms and the stoppage of urine, but he has much to say about this use for pregnant women: "Dame Venus was minded to pleasure women with child by this herb for there grows not an herb fitter for their use than this is ... This herb bruised and applied to the navel, stays miscarriages; I know no herb like it for that use; boiled in ordinary beer and the decoction drank, doth the like; and if her womb be not as she would have it, this decoction will make it so. Let those women that desire children, love this herb, it is their best companion, (their husbands excepted)."
Mrs. Grieve (Ref. #7) goes into more detail about the cakes (or Tansies) that Gerard writes about and she gives a recipe. Around Easter time these cakes were a tradition to help ward off the ill-effects from the Lenten fasting during the cold days of Winter.
Toxicity: Despite the centuries of herbal medicine use, the plant is dangerous. In the United States the FDA prohibits the sale of food or medicine containing tansy. Tilford (Ref. #39) stated: "Anything in the plant kingdom that can kill intestinal parasites can certainly cause harm to humans."
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"