genus Achillea - perennial often aromatic and sometimes mat-forming herbs of north temperate regions: yarrow; milfoil

Achillea millefolium, milfoil, yarrow - ubiquitous strong-scented mat-forming Eurasian herb of wasteland, hedgerow or pasture having narrow serrate leaves and small usually white florets; widely naturalized in North America

Achillea ptarmica, sneezeweed yarrow, sneezewort - Eurasian herb having loose heads of button-shaped white flowers and long gray-green leaves that cause sneezing when powdered

herb, herbaceous plant - a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests