St Charles County Master Gardeners
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Yarrow (Common Milfoil)
A hairy, aromatic perennial with a simple or branching stem. Flowerheads minute, in dense, flat-topped, terminal clusters. Ray florets minute, white, rarely light pink, disk florets light yellow. Blooms May–November. Leaves finely dissected, fernlike, to 10 inches long, narrow-oblong, alternate. The odor is distinctively sweet and rather soapy, akin to the smell of chrysanthemums.
Several cultivars have been developed for the gardener, with a variety of flower colors.
Height: to 2½ feet.
Habitat and conservation:
Occurs in fields, pastures, prairies, roadsides, waste places, and disturbed sites. It is native to North America, Europe, and Asia. With its strong odor and host of potent chemicals, it has had many spiritual and medicinal uses in human cultures across the world. Its wild forms can be weedy to the point of invasiveness, but many horticultural varieties have been developed that are easier to manage in gardens.
Distribution in Missouri:
Yarrow has a long history as a medicinal plant in China, Europe, and North America. In China, it was used for fortune-telling in the I Ching. Europeans long ago used it in magical amulets; today they use it in sheep fodder. Yarrow was found at a Neanderthal burial site in northern Iraq.
Many insects visit the flowers for nectar and pollen, and others eat the leaves. Researchers have found that some cavity-nesting birds, including starlings, line their nests with yarrow, whose aromatic chemicals may inhibit parasites.