Tanacetum

Tanacetum is a genus of flowering plants in the aster family (Asteraceae) comprising about 160 species of herbaceous perennials and subshrubs native to temperate regions of Europe, Asia, and North Africa, with many species widely cultivated or naturalized elsewhere. The plants are typically aromatic and often have pinnately dissected leaves; they usually form upright clumps and can vary in size from compact to tall.

Most Tanacetum species produce heads of small flowers arranged in cymes or flat-topped inflorescences. Heads generally have yellow to creamy disk florets, and most lack prominent ray florets, giving a button-like appearance. The common tansy (Tanacetum vulgare) is tall with feathery leaves and bright yellow, buttonlike heads. Feverfew (Tanacetum parthenium, formerly Chrysanthemum parthenium) has delicate leaves and small white to yellowish flowers.

Taxonomically, Tanacetum belongs to the tribe Anthemideae within the subfamily Asteroideae of Asteraceae. Several species previously placed in Chrysanthemum have been reassigned to Tanacetum, reflecting changes in classification and phylogeny.

Uses and safety: Several species are cultivated as ornamentals for their foliage and long-lasting blooms. Feverfew has a long history in traditional medicine for migraine prophylaxis; its active constituent, parthenolide, has been studied for anti-inflammatory effects. Many Tanacetum species produce essential oils rich in terpenoids; some oils contain thujone and can be toxic if ingested or used improperly. Contact dermatitis can occur in sensitive individuals. Medicinal use should be supervised by professionals, and handling should be cautious with some species.

Cultivation: Tanacetum species prefer full sun and well-drained soils, are generally hardy in temperate climates, and can spread via seed or division. In gardens they can be vigorous and may require management to prevent spread.