Achillea lanulosa (western yarrow) is so similar to common yarrow that some authorities consider them to be the same species, although technically Achillea lanulosa is native and Achillea millefolium is European. Note the flat-topped clusters of small, white flowers and the fern-like aromatic leaves. These species can grow in a great variety of pasture, range, and wasteland situations from sea level to 10,000 feet. Although this species is common, it is not particularly aggressive and is often symptomatic of over-grazing. Pink flowered forms are cultivated and occasionally occur in nature.