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11 <br />Forbs <br />Achillea lanulosa <br />(Western Yarrow) <br />Western yarrow is one of the most widely distributed and abundant herbaceous spe- <br />cies in the 11 far western States. Its range includes large areas in southern <br />Canada from British Columbia to Manitoba, a few of the Lake States, and all the <br />States west of North Dakota and south into Mexico. <br />This species prospers in a great variety of habitats, such as sagebrush areas, <br />canyon bottoms, glades, roadsides, and vacant lots. It is also prevalent in <br />brushlands, aspen, and open timper , but avoids dense shade. It is comparatively <br />drought -resistant and flourishes in the sandy and gravelly loam soils of open <br />flats, parks, and dry meadows. The plants usually grow somewhat scatteringly, <br />seldom forming pure stands on areas larger than a few square rods. In places <br />where the natural plant cover has been but slightly or not all all disturbed, <br />• western yarrow occurs only sparsely, but it is one of the plants that invades <br />readily and increases conspicuously when overgrazing makes growing conditions <br />unfavorable for more palatable and less resistant species. <br />The forage value of western yarrow varies greatly with different localities and <br />with different plant associates. On many ranges all classes of livestock graze <br />this plant moderately throughout the season. Sheep (and sometimes cattle) often <br />evince a fondness for the flower heads of western yarrow. They do not relish the <br />stems when these parts become somewhat woody late in the season, although they <br />occasionally graze the dried leaves. The species rates from poor to, rarely, <br />good in palatability for sheep and from unpalatable to fair, seldom fairly good, <br />for cattle. Its chief value for sheep appears to be in Nevada and New Mexico, <br />although ranking as fairly good in parts of Utah and Arizona. It appears to be <br />most valuable for cattle in parts of Colorado, Wyoming, Arizona, and New Mexico. <br />In California it is usually regarded as poor or worthless. Horses graze it much <br />less than do cattle. Deer, as a rule, eat western yarrow very sparingly, but on <br />the Kaibab Plateau the species is regarded as fair mule -deer forage. <br />2-82 <br />