- Name also: Common Tansy
- Family: Daisy Family – Compositae, subfamily Asteroideae
(formerly Aster Family – Asteraceae)
- Growing form: Perennial herb. Rootstock branching.
- Height: 30–150 cm (12–60 in.). Stem woody at base, rigid, branching, almost glabrous, usually reddish brown. Strong herb-like fragrance.
- Flower: Single flower-like, usually 7–11 mm (0.28–0.44 in.) capitula, surrounded by involucral bracts. Capitula’s ray-florets lacking; disc florets deep yellow, tubular, small. Stamens 5. Pistil of 2 fused carpels. Involucral bracts in 3 rows, with ragged margins, glabrous. Capitula 10–60 borne in a dense corymbose cluster.
- Leaves: Alternate, stalkless–short-stalked. Blade usually pinnately lobed, sparsely haired, dotted with glands, lobes lanceolate, with tapered tips, serrated–pinnately lobed. Sometimes blade 2 times pinnately lobed, lobes densely toothed, crinkled (f. crispum).
- Fruit: Many-ridged achene, tip with shallow, crowned by a low membranous ring.
- Habitat: Gravelly and stony sea-shores, bird rocks, roadsides, rocky outcrops, inland often around inhabited areas. Also ornamental, in many places left over and an escape from old gardens.
- Flowering time: July–September(–October).
Tansy only grows in Finland as a native plant on rocky seashores, but it has travelled inland along roadsides as far as the Arctic Circle and sometimes even further north. In bygone times it was transplanted close to inhabited areas as a medicinal, culinary and ornamental herb. Tansy was used as a very versatile medicinal to e.g. expel roundworms and threadworms and ease digestive and nervous disorders. As with other medicinal herbs, close familiarity with the plant’s properties helps it be used safely. The strong smell that comes from the shoots is due to their oil, which contains poisonous thujone. Tansy contains chemically different kinds of stands, some of which cause severe poisoning symptoms, and even death. This requires the ingestion of a large amount of shoots, however.
According to one particular theory, the scientific name of tansy’s genus comes from the Greek word for ‘deathless’. Tansy has been used in the embalming process and has been a common graveyard plant in Finland too. In the old days it was used to flavour stews, baking, salads and – of course – strong spirits. It has also been used as a tobacco substitute and to dye wool, and it helps compost decompose more quickly. It has been shown to keep pests away from fruit trees and perennials and when it is dries it repels moths, flies, midges and ants from indoor places. Especially in Lapland, where the choice of undemanding and easily-cared-for perennials is not so large, tansy grows in every yard and has held onto its spot as a natural perennial in the flower-bed. Its strong stems stick up during the winter, and as they keep well, tansy also makes a pleasant dried flower.
In the south of Finland, apart from the wild form which may seem very mundane, a beautifully-leaved variety, ‘crispum’ has been cultivated, but it blooms poorly.