Yarrow is a member of the Aster Family, it grows as a herbaceous perennial with leaves and flower stalks arising from creeping underground or near-surface rootstocks. The aromatic fern or feather-like leaves are finely divided and feel soft. Most of the leaves are clustered at the base of the flowering stalk. These leaves are mainly 10 to 15 cm long.
The plant appears grayish-green because it is covered by many small hairs. Tiny flowers crowd into flat-topped clusters atop stalks that are up to 100 cm high. Each tiny flower in the cluster consists of up to 8 ray flowers with a strap-shaped petal and disk flowers that have only reproductive parts. The flowers are white to pinkish and bloom from May to October depending on the local climate. The flower tops dry and turns brown by the end of summer, producing many one-seeded, smooth, and flattened fruits.
It prefers well-drained, open sites such as roadsides, meadows, and rocky slopes. It grows from low to high elevations and often becomes weedy at low elevations. It thrives in coastal meadows, the arid sagebrush steppe of the interior, as well as dry alpine sites. You can find it throughout British Columbia and over much of North America. It also occurs across northern and Central Europe and Asia.
Strongly scented, it was widely known to folk throughout the Northern Hemisphere as medicinal. The strongly scented volatile oil has antibacterial properties. Scottish Highlanders made yarrow ointment for wounds. In the Orkney Islands, yarrow tea was drunk to dispel melancholy. Strong tea was considered a good remedy for colds and fevers.
Many native elders of B.C. value yarrow as a medicine especially to treat sores. First people soaked the leaves in hot water, then used them in a poultice for sore muscles. This same poultice could be used to treat saddle sores on horses.
Washed and crushed roots were recommended for toothaches. Various teas and concoctions were prepared for internal problems and as a general tonic. Fresh leaves crushed and rubbed on the skin or put in a fire acted to repel mosquitoes. Herbal users should be aware that yarrow is phototoxic and skin exposed to yarrow may become irritated when exposed to strong sun.