Yarrow :

Milfoil, Common Yarrow

Achillea millefolium
NATIVE

Description (Jepson, PlantID.net)

Eudicotyledon
- Eudicots are a major lineage of flowering plants; see family for general characteristics
Sunflower Family (Asteraceae)
Herbaceous perennial
Leaves
- Alternate (1 leaf at each junction with stem) and compound (divided into leaflets)
- Fern-like, with varying degrees of hairiness
- Aromatic
Flowers
- Inflorescence (flower arrangement) is a branching, flattened dome of many composite flowerheads
- Each radiate flowerhead (see Sunflower family) has
  - 3-8 outer white 3-lobed ray flowers, suggesting petals
  - 15-40 central white disk flowers, with orange stamens (male flower parts)
- Phyllaries (vase-like floral bracts, collectively called the involucre) in 3-4 rows
- Ovary inferior (below the attachment of other flower parts)
Fruit is an achene (a single-seeded, dry fruit that does not split open)
Height 8-16 in.

Distribution

Native to California
- Grows in woodlands, forests, and grasslands, especially in disturbed areas
- See Calflora for statewide observations of this plant
Circumboreal, occurring throughout the Northern Hemisphere
Grows at elevations to 12,000 ft.

Uses (San Mateo County Parks prohibits removal of any natural material)

Some cavity-nesting birds, e.g., European starlings, use leaves to line their nests
Food source for many insects, including bees and butterflies, e.g. the Lorquin admiral (Limenitis lorquini), west coast lady (Vanessa annabella), western brown elfin (Incisalia augustinus iroides), and gray hairstreak (Strymon melinus) butterflies
Native people
- Used for a variety of ailments, e.g. fever, toothaches, earaches, general pain relief, and burns
Long history of medicinal use because of its astringent effects
- One of the medicinal herbs found at a 60,000-year-old Neanderthal burial site in Iraq
- Many of its common names, like woundwort, bloodwort, stanchwort, carpenter’s weed, sanguinary, herba militaris, and nosebleed, suggest its use to stanch the flow of blood
CAUTION – Yarrow is toxic to dogs, cats, and horses (ASPCA 2022)

Name Derivation

Achillea (ak-ILL-ee-a) – named for the Greek hero Achilles: according to Greek mythology, Achilles used yarrow to treat the wounds of his soldiers
millefolium (mil-eh-FO-lee-um) – from the Latin for “thousand leaves,” referring to the finely dissected leaves
Yarrow – from the Old English gearwe, of uncertain origin; cognate of Old High German garwa and Dutch gerwe

Notes

Flowers at Edgewood are white, but yarrow comes in shades of pink as well!
Jepson notes that yarrow is highly variable, especially in leaf size and hairiness
May become weedy or invasive in some regions or habitats (Hurteau 2006)

ID Tips

May be confused with golden-yarrow (Eriophyllum confertiflorum var. confertiflorum), also in the Sunflower family, and with yampah (Perideridia kelloggii) in the Carrot family

	Yarrow	Golden-yarrow	Yampah
Growth Habit	herbaceous perennial	small evergreen shrub	herbaceous perennial
Leaves	finely-cut, fernlike leaflets	deeply-lobed, silver grey to woolly	narrow, blade-like leaflets (wither before flowers appear)
Inflorescence	flattened dome of flowerheads	dense clusters of flowerheads	double umbel¹ of uncrowded flowerheads
Flower Color	white to pink	golden yellow	white

¹ Flowers arranged on a double set of stalks, each set radiating from a single point

Yarrow (L), Golden-yarrow (M), Kellogg’s Yampah (R)
© DSchiel (L, M), KKorbholz (R)

At Edgewood

Found in serpentine and non-serpentine grasslands and open woodlands
- See iNaturalist for observations of this plant
Flowers April – July

See General References

Specific References

American Society for the Prevention of Cruelty to Animals (ASPCA) 2022. Yarrow.

Shapiro, A.M. and T.D. Manolis. 2007. Field Guide to Butterflies of the San Francisco Bay and Sacramento Valley Regions. University of California Press, Berkeley and Los Angeles, California.

Hurteau, M., and R. Briggs. 2006. Common yarrow Achillea millefolium L. Plant Fact Sheet. United States Department of Agriculture, Natural Resources Conservation Service, National Plant Data Center, Plant Materials Center, Bridger, Montana.