Tanacetum vulgare L.
Chrysanthemum vulgare (L.) Bernh.
Tanacetum boreale Fisch. ex DC.
Tanacetum vulgare L. var. crispum DC.
Common tansy, golden buttons, curly leaf tansy, tansy, bitter buttons
Common tansy is native to Eurasia, but widespread throughout cooler parts of North America, probably introduced by settlers who valued its alleged medicinal properties. (The name “tansy” derives from the Greek ἀθανασία, or athanasia, meaning immortality: it was once used for embalming in hopes of achieving this.) It is common in disturbed sites such as roadsides, river banks, out-of-use sites, and old fields, preferring bright sun. Many plant it in gardens. In some habitats tansy is considered invasive.
Plants: Plants are robust perennials reaching 6½' (2 m) in size, though most are under 3' (1 m). Stems grow singly or in clusters, and are coarse, grooved, and angular, branching near the top. Roots are woody and often coiled.
Leaves: Leaves are alternate, very finely divided, and toothed. They smell like camphor when crushed, and are 2-12" (5-30 cm) long. The odor is variously described as “rank” or “aromatic.” (If you crush the leaves and don’t smell this odor, there’s a good chance you have the similar-appearing Tanacetum bipinnatum subsp. huronense, which is endangered or threatened in some locales.)
Flowers: Flowerheads are composed of dense flat-topped clusters of 20-100 yellow disk florets, each up to ½" (1.3 cm) around. The individual florets are often likened to buttons. Most florets resemble the center of a daisy, and lack the daisy’s “petals,” technically called ray flowers. Some tansy florets have short ray flowers though. Tansies bloom from from July to October.
Fruits: Florets produce many achenes ¹/₃₂-¹/₁₆" (1-1.8 mm) long.
Edibility: Poisonous Causes a rapid, weak pulse and stomach pains in lower doses, and can cause death in larger quantities. Leaves are bitter-tasting, and avoided by many (but not all) livestock. In small quantities young leaves and flowers, soaked in water, are used sparingly as a substitute for sage, to flavor dishes.
Medical: Tansy was once widely used for a variety of ailments, but modern herbalists generally avoid it. It contains thujone, also present in the wormwood from which the spirit absinthe is made. Thujone is a GABAA receptor antagonist, toxic to brain, kidney, and liver cells, causing muscle spasms and convulsions in larger amounts. Thujone was once thought to stimulate cannabinoid receptors, thus causing some of the same symptoms as marijuana, but this has since been proven false.
Tanacetum vulgare on the USDA Forest Service's Fire Effects Information Database
Tanacetum vulgare at the Minnesota Department of Natural Resources
Tanacetum vulgare on plants.ces.ncsu.edu
Tanacetum vulgare on www.webmd.com
Tanacetum vulgare description by Thomas H. Kent, last updated 25 May 2020.
Range: Zones 3-9: