Common yarrow is a perennial plant that thrives in the United States, Europe and Asia. It grows throughout the U.S. and Native Americans had many uses for this wildflower. It is weedy in nature but produces an attractive flower that has some use in wildflower gardens. Also known as milfoil, common yarrow is a member of the Aster family of plants, as is the western yarrow, a species native to the western half of the U.S.
Common yarrow can be an invasive plant since it reproduces through a series of underground stems called rhizomes. It grows to 16 inches high in some instances and has hairy leaves. Those leaves closest to the bottom portion of the stem grow to the largest sizes. Yarrow has a pungent smell to it but the odor is not overwhelming to the point of being unpleasant. In the wild, it grows in fields, in open woodlands and in waste places such as near old buildings or along the side of the road.
The flowers of common yarrow grow in flat-topped clusters. They are small and grow close together. The head of the yarrow flower is only about a quarter inch in width, with from four to six small rays surrounding it. The color of common yarrow is off-white and the plant blooms from June into the late summer months.
Common yarrow is extremely tolerant of dry conditions, which makes it a good fit for those parts of your garden you have trouble keeping moist. Many ornamental cultivars of common yarrow are available from seeds, which should be planted about a quarter inch deep, according to the USDA's Natural Resources Conservation Service website. Without sufficient sunlight, the seeds will not sprout, and they require warmth within the range of 65 to 75 degrees F to grow. Since common yarrow can develop rhizomes, it has the ability to spread to other parts of your property if you are not vigilant.
Western yarrow is not invasive in nature and like common yarrow is resistant to drought. The flowers of western yarrow range from pure white to a cream color and have the same shape as common yarrow. Western yarrow has fernlike leaves, with the leaves being even hairier than those of the common variety. In some cases, western yarrow may be as tall as 3 feet.
The Native Americans employed parts of common yarrow to treat fevers, help stop bleeding and to alleviate itchiness in rashes. When steeped in boiling water, the leaves produce a tea that can quiet an upset stomach. Western yarrow leaves had the same effect and the plant had uses as a repellant for mosquitoes and in poultices to aid wounds that were infected.