Plants occur at elevations up to 10,500 ft. The plants can be identified at long distances because of the large flat-topped clusters of white flower heads. In our area, yarrow is from one to two feet tall. Stems are unbranched except at the very top and are perennial from short horizontal rhizomes. The narrow leaves are divided into hundreds of fine segments and remind one of green feathers.
Fruits are tiny, flattened achenes as in the sunflower.
The effects of cattle grazing on yarrow seem to vary regionally. Yarrow has an extensive and interesting literature. Most intriguing is that a random selection of stalks of the humble yarrow was selected by the ancient Chinese sages as the means to consult the oracles of the I Ching or Book of Changes. This compendium arose from mythical antiquity and contains the seasoned wisdom of thousands of years of human history. The healing powers of yarrow were said to have been discovered by the Greek warrior Achilles.