Sweet yarrow

Achillea ageratum L. (Asteraceae) is an aromatic, gently scented perennial herb native to the western Mediterranean basin (Iberian Peninsula, southern France, Italy, North Africa) and naturalised in scattered localities elsewhere in temperate Europe, growing 20–60 cm tall from a creeping rhizomatous rootstock. Stems are erect, slender, leafy, and finely pubescent. Leaves differ from those of common yarrow in being undivided: they are alternate, sessile, linear-oblong to narrowly oblanceolate, 2–6 cm long, with finely serrate to crenate margins, bright green, and slightly fleshy with a sweet balsamic fragrance when bruised. The inflorescence is a dense flat-topped compound corymb of numerous small heads, each 4–6 mm across with 4–7 short, broad, pale-yellow ray florets surrounding a similarly yellow disc. Achenes are small and obovate without a pappus. Flowering occurs from late spring to early autumn.