Common Yarrow

Achillea millefolium

Common Yarrow (Achillea millefolium) is a native perennial of the sunflower family, with soft, feathery, strongly scented leaves and flat-topped clusters of tiny white flower heads. It blooms from June into September and is one of the most widespread wildflowers in the Black Hills, from the prairie foothills to the high country, and the National Park Service lists it at Wind Cave, Jewel Cave, Mount Rushmore and Devils Tower.

Free photos from other sources

Common Yarrow: Flat white cluster of tiny flower heads above feathery leaves — Achillea millefolium. Jared Shorma, CC BY 4.0, resized. Get it at the source

Common Yarrow: Close-up of flower heads, each with a few white rays and a cream center — Achillea millefolium. William Michael O'Boyle, CC BY 4.0, resized. Get it at the source

Common Yarrow: Gray-green, finely divided, feathery leaves — Achillea millefolium. Jason Leduc, CC0 1.0. Get it at the source

Common Yarrow: Young plant with feathery leaves and opening flower clusters — Achillea millefolium. Brooke Smith, CC BY 4.0, resized. Get it at the source

Common Yarrow: White flower clusters in a grassy meadow — Achillea millefolium. Brian Dickerson, CC0 1.0. Get it at the source

Common Yarrow: Dry brown seed heads held in a hand in winter — Achillea millefolium. Eric Schmidt, CC BY 4.0, resized. Get it at the source

Quick facts
Family	Asteraceae · Aster
Status	Native perennial
Blooms	June into September
Height	30–100 cm (12–40 in)
Where	Open, sunny ground: prairie, meadows, pine openings, rocky slopes and roadsides
Also called	Western Yarrow, Woolly Yarrow, Milfoil, ȟaŋté čhaŋȟlóǧaŋ (Lakota), tȟaópi pȟežúta (Lakota)
Synonym	Achillea lanulosa, Achillea millefolium var. lanulosa, Achillea millefolium var. occidentalis, Achillea borealis, Achillea gracilis
Toxicity	It contains volatile oils, alkaloids and glycosides, but it is not generally considered toxic because livestock seldom eat it.
Traditional use	Sitting Bull College's 1998 Culturally Important Plants of the Lakota says it was used as a poultice for wounds and bites, chewed for toothache, put in the ear as a plug of moistened leaves for earache, and made into a leaf tea for stomach ache, cough and sore throat.
Note	Black Hills plants are the native western form; European garden strains also turn up near towns and on reseeded roadsides.

Roots, seeds & germination

Root: Fibrous roots plus long, branching rhizomes just below the surface, which let one plant spread into a patch. Broken rhizome pieces can resprout from as deep as 30 cm (12 in), which is why yarrow comes back quickly along trails and after fire.

Seed: Tiny, flattened, gray-brown achenes about 2 mm (1/12 in) long, with no fluff. A single flowering stem can make several thousand, and most fall within 1–2 m (3–6 ft) of the parent. The dry brown seed heads often stand into winter.

Germination: Easy. Fresh seed needs no treatment and sprouts in about 2–14 days. It needs light, so it is pressed onto the surface or covered no more than 3–6 mm (⅛–¼ in), and the NRCS plant guide suggests a month of cold, moist stratification for best results.

How do you identify Common Yarrow?

Look for a flat or slightly domed cluster 5–10 cm (2–4 in) across, made of many tiny flower heads, each about 4–6 mm (¼ in) across with a few short, broad white rays around a cream to pale yellow center. The leaves are cut into many very fine segments, so each looks like a feather, and they are usually soft and woolly-gray, with a strong, sharp, sage-like smell when crushed. Poison Hemlock and Water Hemlock carry white flowers in true umbels, with all the flower stalks spreading from one point and plain five-petaled flowers with no daisy center, on much larger plants with broader, divided leaflets.

When does it bloom?

June into September.

Where does it grow?

Open, sunny, usually well-drained ground: mixed-grass prairie, mountain meadows, ponderosa pine openings, aspen stands, rocky slopes, trailsides and roadsides, but not dense shade. The Black Hills National Forest says it grows throughout the Black Hills, and herbarium specimens from Lawrence, Pennington, Custer, Meade and Fall River counties and Crook and Weston counties in Wyoming range from about 1,100 to 2,160 m (3,600–7,100 ft). The National Park Service lists it at Wind Cave, Jewel Cave, Mount Rushmore and Devils Tower, and iNaturalist also has records from Custer State Park.