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| ## western yarrow {#western-yarrow .Title-Header}                     |
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| *Achillea millefolium* L. var. *occidentalis* DC.                     |
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| Plant Symbol = ACMIO                                                  |
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Contributed by: USDA NRCS Bridger Plant Materials Center

![](media/image2.jpeg){width="2.7916666666666665in"
height="1.9583333333333333in"}

##### Alternate Name {#alternate-name .Header-3}

Woolly yarrow

##### Uses {#uses .Header-3}

*Conservation:* It is an early successional species that readily
establishes on disturbed sites. Western yarrow is recommended for adding
species diversity in native seed mixtures for rehabilitation of
disturbed sites such as rangelands, minelands, roadsides, park and
restoration areas, prairie reconstruction projects, and farm bill
program conservation plantings. Secondary use is for ornamental
application in pollinator friendly, low maintenance, or naturalized
landscapes.

*Forage:* It is a food source for bighorn sheep, pronghorn antelope, and
deer. Sage grouse, especially chicks, and other upland birds rely
heavily on the foliage of western yarrow as a food source. Domestic
sheep and goats derive a fair amount of forage value from western
yarrow, while cattle and horses mostly graze the flower head. The
volatile oils, alkaloids, and glycosides are considered toxic, but the
plant is seldom overgrazed by foraging animals.

*Ethnobotanic:* Native Americans used western yarrow for many purposes,
such as a tea to cure stomach ailments, a poultice on infected wounds,
and as a mosquito repellant.

##### Status {#status .Header-3}

Please consult the PLANTS Web site and your State Department of Natural
Resources for this plant's current status (e.g. threatened or endangered
species, state noxious status, and wetland indicator values).

##### Weediness {#weediness .Header-3}

Western yarrow is not to be confused with the introduced, invasive
plant, common yarrow (*Achillea millefolium* var. *millefolium*). Common
yarrow has origins in Eurasia, the European continent, and the islands
of Scandinavia. This introduced species is considerably different from
western yarrow in that it has a much taller stature, aggressive vigor
and weediness characteristics, and initiates a later sequence of
flowering and seed ripening. Please consult with your local NRCS Field
Office, Cooperative Extension Service office, or state natural resource
or agriculture department regarding its status and use. Weed information
is also available from the PLANTS Web site at plants.usda.gov.

##### Description  {#description .Header-3}

Western yarrow is a native, herbaceous perennial in the Aster Family. It
is a very common wildflower that grows erect from creeping rootstocks,
to a height mostly 10 to 36 in. (25 to 90 cm) tall. The leaves of
western yarrow are densely hairy, and lacy and fern-like in appearance,
as they are finely dissected into numerous, short and narrow divisions
not over 0.04 in. (1 mm) wide\--millefolium means a thousand leaves in
Latin. Common yarrow leaves, in comparison, are smooth or only sparsely
hairy; and the leaf segment is longer, more rounded, and lance-shaped.
The somewhat rounded terminal clusters of flower heads of western yarrow
are normally white to cream-colored and have an extended bloom period
from May to September. For a current distribution map, please consult
the Plant Profile page for this species on the PLANTS Web site.

##### Adaptation {#adaptation .Header-3}

Western yarrow is one of the most widely recognized and adaptable
wildflowers in the western United States. Its range of distribution
includes many habitats across Canada, the Great Plains, and the western
United States. Western yarrow is very drought-tolerant and exhibits good
survival in droughty conditions on gravelly loam and thin or sandy
soils.

#####  {#section .Header-3}

##### Establishment {#establishment .Header-3}

Seed of western yarrow is non-dormant and readily germinates when spring
planted at a very shallow depth. It tends to be less competitive in
early development and becomes more so with age. Western yarrow produces
very few flowers the establishment year, but will easily set seed in
subsequent years. It is moderately rhizomatous, developing as a
scattered colony that maintains a semi-evergreen state when dormant.

##### Management {#management .Header-3}

New seedings may need protection from trampling and some weed control
during establishment. Western yarrow vigor, esthetics, and stand
persistence after establishment may be sustained with properly timed
grazing or defoliation of associated species.

##### Pests and Potential Problems {#pests-and-potential-problems .Header-3}

Inflorescences that are harvested for seed production often contain
small quantities of insect larvae and numerous live insects. There is no
apparent short- or long-term effect on the seed in any way. Many
beneficial and pollinating insects, such as minute pirate bug (*Orius*),
big-eyed bug (*Geocoris*), hoverflies (Syrphidae), and several tachnid
flies (*Archytas apicifer*, *Gymnosoma*, *Tricopoda pennipes,
Cylindromia*) are known to frequent yarrow plants. Pest insects include
common leaf bugs (*Lygus*.) and flea beetles (Chrysomelidae). Root rot
and mildew may occur in poorly drained soils.

##### Environmental Concerns {#environmental-concerns .Header-3}

This plant is a common component of such ecological sites as shallow,
silty, shallow to gravel, and silty steep. Associated species include
western wheatgrass (*Pascopyrum smithii*), bluebunch wheatgrass
(*Pseudoroegneria spicata*), prairie Junegrass (*Koeleria macrantha*),
Sandberg bluegrass (*Poa secunda*), common gaillardia (*Gaillardia
aristata*), big sagebrush (*Artemisia tridentata*), and prairie
coneflower (*Ratibida columnifera*). Western yarrow is a pioneer species
and considered an increaser where the forage resource has been over
utilized. It is seldom regarded as a problem weed except on heavily
disturbed, arable sites with favorable environmental conditions. Western
yarrow should be considered noninvasive when used within a diverse plant
community in its anticipated area of adaptation.

##### Cultivars, Improved, and Selected Materials (and area of origin) {#cultivars-improved-and-selected-materials-and-area-of-origin .Header-3}

Great Northern Germplasm is a selected class release of western yarrow
originally collected in 1988 in Flathead County, Montana. This 2004
release was selected for top performance in vigor, height, seedhead
production, and survival from among 29 accessions of native yarrows from
Montana and Wyoming. It is adapted for use in northern Idaho, and all of
Montana and Wyoming, except the Red Desert and Bighorn Basin. G~1~ seed
(analogous to Foundation seed) will be maintained by the USDA-NRCS
Bridger Plant Materials Center and is available to commercial growers
through the Foundation Seed Program at Montana State University-Bozeman
and the University of Wyoming Foundation Seed Service at Powell,
Wyoming. Commercial production is limited to two generations beyond
G~1~.

Yakima Germplasm is a source-identified, composite release of western
yarrow from 27 collection sites on the U.S. Army Yakima Training Center
in Yakima, Washington. Yakima Germplasm western yarrow is intended for
use in the rehabilitation and restoration of western rangelands. The
USDA-ARS Forage and Range Research Laboratory, Logan, Utah, will
maintain G~1~ seed and it will be made available to growers through the
Utah Crop Improvement Association. Seed through the G~4~ generation will
be eligible for certification.

##### Prepared By:  {#prepared-by .Header-3}

*Susan R. Winslow*

USDA NRCS Plant Materials Center, Bridger, Montana

##### Species Coordinator:  {#species-coordinator .Header-3}

*Susan R. Winslow*

USDA NRCS Plant Materials Center, Bridger, Montana

##### Edited: 2Sept2005 RLN; 08dec05 jsp; 30may06jsp {#edited-2sept2005-rln-08dec05-jsp-30may06jsp .Header-4}

For more information about this and other plants, please contact your
local NRCS field office or Conservation District, and visit the PLANTS
Web site\<[http://plants.usda.gov](http://plants.usda.gov/)\> or the
Plant Materials Program Web site
\<[http://Plant-Materials.nrcs.usda.gov](http://Plant-Materials.nrcs.usda.gov/)\>

*The U.S. Department of Agriculture (USDA) prohibits discrimination in
all its programs and activities on the basis of race, color, national
origin, sex, religion, age, disability, political beliefs, sexual
orientation, and marital or family status. (Not all prohibited bases
apply to all programs.) Persons with disabilities who require
alternative means for communication of program information (Braille,
large print, audiotape, etc.) should contact USDA\'s [TARGET
Center](http://www.usda.gov/oo/target.htm) at 202-720-2600 (voice and
TDD).*

*To file a complaint of discrimination write USDA, Director, Office of
Civil Rights, Room 326-W, Whitten Building, 14th and Independence
Avenue, SW, Washington, DC 20250-9410 or call 202-720-5964 (voice or
TDD). USDA is an equal opportunity provider and employer.*

*Read about [Civil Rights at the Natural Resources Convervation
Service](http://www.nrcs.usda.gov/about/civilrights/).*