tansy (EwA Guide to the Plants of the Fells (US))

tansy

Tanacetum vulgare

Summary ⁷

Tansy (Tanacetum vulgare) is a perennial, herbaceous flowering plant of the aster family, native to temperate Europe and Asia. It has been introduced to other parts of the world including North America, and in some areas has become invasive. It is also known as common tansy, bitter buttons, cow bitter, or golden buttons.

Description ⁸

Perennials, mostly 40–150 cm. Stems 1–2+ (ridged), erect, branched distally (glabrous or sparsely hairy). Leaves basal (soon withering) and cauline; petiolate or sessile; blades broadly oblong or oval to elliptic, 4–20 × 2–10 cm, pinnately lobed (rachises ± winged, primary lobes 4–10 pairs, lance-linear to lanceolate or narrowly elliptic, often pinnately lobed or toothed), ultimate margins dentate, faces glabrous or sparsely hairy, gland-dotted. Heads 20–200 in compact, corymbiform arrays. Involucres 5–10 mm diam. Receptacles convex to conic, epaleate. Ray florets 0 (heads disciform, peripheral pistillate florets ca. 20; corollas yellow, lobes 3–4). Disc corollas 2–3 mm. Cypselae 1–2 mm, 4–5-angled or -ribbed, gland-dotted; pappi coroniform, 0.2–0.4 mm. 2n = 18.