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), more specifically called a cypsela because of the inferior position of the ovary, without pappus
• 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

At Edgewood

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

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.

General References

Calflora Database. 2014. Berkeley, California.

Calscape. 2018. California Native Plant Society.

Charters, M.L. 2015. California Plant Names: Latin and Greek Meanings and Derivations.

Charters, M.L. 2017. Southern California Wildflowers: Guide to the Pronunciation of Specific, Generic and Family Names.

Corelli, T. 2004. Flowering Plants of Edgewood Natural Preserve (2nd. ed.). Monocot Press, Half Moon Bay, California.

Dave’s Garden.

Elpel, T.J. 2013. Botany in a Day: The Patterns Method of Plant Identification. HOPS Press, Pony, Montana.

Flora of North America. efloras.org.

Harris, J.G., and M.W. Harris. 2013. Plant Identification Terminology: An Illustrated Glossary. Spring Lake Publishing, Spring Lake, Utah.

Keator, G. 2009. California Plant Families. University of California Press, Berkeley and Los Angeles, California.

Native American Ethnobotany DB.

Regents of the University of California. Jepson eFlora. Jepson Herbarium. University of California, Berkeley.