Achillea millefolium or yarrow is a flowering plant in the family Asteraceae, native to the Northern Hemisphere. In New Mexico and southern Colorado, it is called plumajillo, or “little feather”, for the shape of the leaves. In antiquity, yarrow was known as herbal militaris, for its use in staunching the flow of blood from wounds. Other common names for this species includecommon yarrow, gordaldo, nosebleed plant, old man’s pepper, devil’s nettle, sanguinary,milfoil, soldier’s woundwort, thousand-leaf (as its binomial name affirms), and thousand-seal.
Common yarrow is an erect herbaceous perennial plant that produces one to several stems (0.2 to 1m tall) and has a rhizomatous growth form. Leaves are evenly distributed along the stem, with the leaves near the middle and bottom of the stem being the largest. The leaves have varying degrees of hairiness (pubescence). The leaves are 5–20 cm long, bipinnate or tripinnate, almost feathery, and arranged spirally on the stems. The leaves are cauline and more or less clasping. The inflorescence has 4 to 9 phyllaries and contains ray and disk flowers which are white to pink. There are generally 3 to 8 ray flowers that are ovate to round. Disk flowers range from 15 to 40. The inflorescence is produced in a flat-topped cluster. Yarrow grows up to 3500m above sea level. The plant commonly flowers from May through June, and is a frequent component in butterfly gardens. Common yarrow is frequently found in the mildly disturbed soil of grasslands and open forests. Active growth occurs in the spring.
Common yarrow is a drought tolerant species of which there are several different ornamental cultivars. Seeds require light for germination, so optimal germination occurs when planted no deeper than ¼ inch (~6 mm). Seeds also require a germination temperature of 18–24 °C (64–75 °F). Common yarrow responds best to soil that is poorly developed and well drained. The plant has a relatively short life, but may be prolonged by dividing the plant every other year, and planting 12 to 18 inches (30–46 cm) apart. Common yarrow is a weedy species and can become invasive. It may suffer from mildew or root rot if not planted in well-drained soil.
Yarrows can be planted to combat soil erosion due to the plant’s resistance to drought.
The herb is purported to be a diaphoretic, astringent, tonic, stimulant and mild aromatic. It contains isovaleric acid, salicylic acid, asparagin, sterols, flavonoids, bitters, tannins, andcoumarins. The plant also has a long history as a powerful ‘healing herb’ used topically for wounds, cuts and abrasions. The genus name Achillea is derived from mythical Greek character,Achilles, who reportedly carried it with his army to treat battle wounds. This medicinal action is also reflected in some of the common names mentioned below, such as Staunchweed and Soldier’s Woundwort.
The stalks of yarrow are dried and used as a randomising agent in I Ching divination.
In the Middle Ages, yarrow was part of a herbal mixture known as gruit used in the flavouring of beer prior to the use of hops.
Old folk names for yarrow include arrowroot, bad man’s plaything, carpenter’s weed, death flower, devil’s nettle, eerie, field hops, gearwe, hundred leaved grass, knight’s milefoil, knyghten, milefolium, milfoil, millefoil, noble yarrow, nosebleed, old man’s mustard, old man’s pepper, sanguinary, seven year’s love, snake’s grass, soldier, soldier’s woundwort, stanch weed, thousand seal, woundwort, yarroway, yerw.
Yarrow has also been used as a food, and was very popular as a vegetable in the seventeenth century. The younger leaves are said to be a pleasant leaf vegetable when cooked as spinach, or in a soup. Yarrow is sweet with a slight bitter taste. The leaves can also be dried and used as a herb in cooking.