yarrow | skymeadows

yarrow (Achillea millefolium)

COMMON NAMES:
common yarrow
yarrow
milfoil
carpenter's weed
western yarrow

SCIENTIFIC SYNONYMS:
Achillea albida Willd.
Achillea alpicola (Rydb.) Rydb.
Achillea ambigua Boiss.
Achillea ambigua Pollini
Achillea anethifolia Fisch. ex Herder
Achillea angustissima Rydb.
Achillea arenicola A. Heller
Achillea bicolor Wender.
Achillea californica Pollard
Achillea ceretanica Sennen
Achillea compacta Lam.
Achillea coronopifolia Willd.
Achillea crassifolia Colla
Achillea cristata Hort. ex DC.
Achillea cuspidata Wall.
Achillea dentifera Rchb.
Achillea eradiata Piper
Achillea fusca Rydb.
Achillea gigantea Pollard
Achillea gracilis Raf.
Achillea haenkeana Tausch
Achillea intermedia Schleich.
Achillea lanata Lam.
Achillea laxiflora A.Nelson
Achillea laxiflora Pollard & Cockerell
Achillea magna All.
Achillea magna Haenke
Achillea magna L.
Achillea marginata Turcz. ex Ledeb.
Achillea megacephala Raup
Achillea nabelekii Heimerl
Achillea nigrescens (E. Mey.) Rydb.
Achillea occidentalis (DC.) Raf. ex Rydb.
Achillea ochroleuca Eichw.
Achillea ossica K.Koch
Achillea palmeri Rydb.
Achillea pannonica Scheele
Achillea pecten-veneris Pollard
Achillea pratensis Saukel & R. Länger
Achillea pseudotanitifolia Wierzb. ex Rchb.
Achillea puberula Rydb.
Achillea pumila Schur
Achillea rosea Desf.
Achillea seidlii J.Presl & C.Presl
Achillea setacea Schwein.
Achillea sordida (W.D.J.Koch) Dalla Torre & Sarnth.
Achillea subalpina Greene
Achillea subhirsuta Gilib.
Achillea submillefolium
Achillea sylvatica Becker
Achillea tanacetifolia Mill.
Achillea tenuifolia Salisb.
Achillea tenuis Schur
Achillea tomentosa Pursh
Achillea virgata Hort. ex DC.
Achillios millefoliatus St.-Lag.
Alitubus millefolium (L.) Dulac
Alitubus tomentosus Dulac
Chamaemelum millefolium (L.) E.H.L. Krause
Chamaemelum tanacetifolium (All.) E.H.L.Krause
Chamaemelum tomentosum (L.) E.H.L.Krause

CONFIRMATION STATUS: Pending confirmation.

TAXONOMY: The currently accepted scientific name for yarrow (or

common yarrow) is Achillea millefolium L. Achillea millefolium is
morphologically variable and has been treated as either a single species
with varieties or as multiple distinct species. At least 58 names have
been used for North American specimens. Some early researchers
thought the native North American plants were taxonomically distin-
guishable from introduced, Old World plants. Other botanists have
treated Achillea millefolium as a cosmopolitan, Northern Hemisphere

complex of native and introduced plants that have hybridized, consti-

tuting a single, highly variable species.

The leaves of Achillea millefolium are deeply divided, forming many
small lobes; this feature is referred to by the specific Latin name,
millefolium, which means 'thousand leaf'. The name of the genus,
Achillea is thought to have arisen as it is said that Achilles used this
herb to treat the wounds of his soldiers. The common name 'yarrow'
derives from the Anglo-Saxon name for the plant, 'gearwe'.

NATIVE STATUS: Native and introduced, United States and Canada.

GENERAL BOTANICAL CHARACTERISTICS:

Habit: This introduced (possibly native) perennial plant is about 1-2' tall

that produces one to several stems (2-10 dm tall) from a fibrous under-

ground horizontal rootstock (rhizome). It is unbranched, except near the

apex, where the flowerheads occur. The central stem is light green, furrow-

ed, and more or less covered with white cobwebby hairs. However, some

plants may have glabrous (smooth, without hairs) stems.

Leaves: The alternate leaves are up to 6" long and 1" across, becoming

smaller as they ascend the stems. Leaves are evenly distributed along the

stem, with the leaves near the middle and bottom of the stem being the

largest. Each fern-like leaf is narrowly ovate-oblong in outline and widest

in the middle; however, it is pinnately compound in form and divided into

linear segments. Among members of the Aster Family, the fern-like foli-

age of yarrow is rather unusual and it has a distinctive odor. Other mem-

bers of the Aster family with this kind of foliage include Anthemis spp.

(mayweeds), Matricaria spp. (chamomile), and Tanacetum vulgare (tansy).

Each leaf segment is pinnately cleft or sharply toothed. Overall leaf dimen-

sions range from 0.5-3 cm wide by 3-15 cm long. The leaves are often

crinkled or curled along their margins, folding upward along the central

vein; but sometimes they are nearly flat. Like the stems, the leaves often

have fine cobwebby hairs, although, again, there is varying degrees of pub-

escence (hairiness). The base of each leaf clasps the stem.

Flowers: The upper stems produce corymbs of small flowerheads. Each

flowerhead is about ¼" across, consisting of 5 ray white ray florets and a

similar number of disk florets that are cream or pale yellow. The floral

bracts are pale green and lanceolate-oblong; they often have cobwebby

hairs. All parts of this plant exude a distinctive aroma that is somewhat

soapy and astringent.

Fruit/Seeds: Each floret is replaced by an achene that is oblong and some-

what flattened; it lacks a tuft of hairs.

Roots: The root system produces abundant rhizomes and vegetative offsets.

REGENERATION PROCESS: Axillary rhizomes of yarrow produce new

plants annually at their apices. Vegetative reproduction occurs when the

rhizomes are fragmented.

HABITAT TYPES: Habitats include mesic to dry prairies, pastures,
grasslands, open forests, fallow fields, grassy waste areas, and edges of
paths, yards, or hedges. Disturbed areas are preferred; yarrow persists
in native habitats to a limited extent. Yarrow was introduced into the
United States from Europe as an ornamental and medicinal plant. How-

ever, a Western form of this species that is smaller in size and woollier

in appearance may be native to North America.

SITE CHARACTERISTICS: The preference is full or partial sun, mesic

to dry conditions, and a somewhat heavy clay-loam soil.

SEASONAL DEVELOPMENT: Yarrow has different flowering periods

depending on where it's located. In the south, it flowers late April to early

July, but in the north it doesn't begin flowering until mid-July and will con-

tinue through mid-September. Regardless when the flowering period begins,

the blooming period lasts about a month.

GENERAL DISTRIBUTION: Yarrow spans the entire continental U.S.

(including Alaska) and every Canadian province.

SKY MEADOWS DISTRIBUTION: To be determined.

IMPORTANCE AND USES: The nectar of the flowers attracts many
kinds of insects, especially flies and wasps. Among the flies are such
visitors as bee flies, syrphid flies (including drone flies), thick-headed flies,
tachinid flies, flesh flies, anthomyiid flies, and others. Halictid and other
short-tongued bees occasionally visitor the flowers, where they suck nectar
and collect pollen. Sometimes Mordella spp. (tumbling flower beetles) are
found on the flowerheads. Because the foliage of yarrow has a bitter and
biting taste, it is rarely consumed by most mammalian herbivores. However,

sheep will eat it when the opportunity arises.

Yarrow has a long history of cultural and medicinal uses. In some eastern

cultures it has been used in the mystical practice of divination. Yarrow

can be distilled to form an oil that possesses known anti-inflammatory and

blood-staunching abilities. It has been used to treat internal bleeding, ex-

cessive menstrual bleeding, high blood pressure, fever reduction and more.

Yarrow was highly regarded for its medicinal properties in Britain in Anglo-

Saxon times, and this may have been a factor with its original introduction

into North America. Several tribes of the Plains region of the United States

including the Pawnee and Chippewa tribes used common yarrow. The

Pawnee used the stalk in a treatment for pain relief. The Chippewa used the

leaves in a steam inhalant for headaches. They also chewed the roots and