Ontario Weeds: Yarrow
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Excerpt from Publication 505, Ontario Weeds,
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Name: Yarrow, Achillea millefolium
L.,
Other Names: achillée mille-feuille,
Common yarrow, Fernweed, Milfoil, herbe à dinde, millefeuille,
Achillea lanulosa Nutt.
Family: Composite or Aster Family (Compositae)
General Description: Perennial, reproducing
by seed and by spreading underground rootstalks, often forming very
dense feathery- or ferny-leaved patches. It is distinguished by
its very finely divided, feather-like or ferny leaves, the dense
patches from its spreading underground root system, its flat-topped
clusters of small flower heads, each head with usually 5 tiny white
ray florets, and its characteristic sage-like aroma. Forms with
pinkish to purplish or yellow flowers are cultivated as ornamental
perennials and may escape to lawns and roadsides.
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![]() B. Flowering stem. |
Stems & Roots: Stems erect, usually
covered with fine woolly hair, about 60 cm (2 ft) tall but up to
100 cm (40 in.) in fertile situations, or very short in lawns or
trampled situations; leaves very numerous at base of plant but fewer
and smaller upwards on the stem, finely divided or feather-like,
lower ones long-stalked, the upper stalkless, alternate (1 per node),
green to grayish-green, finely woolly to silky-hairy.
Flowers & Fruit: Flower heads
very small but numerous in dense, flat-topped to rounded clusters,
each head 3 - 7 mm (1/8- ¼ in.) across, ray florets usually
only 5 per head, white or rarely pinkish; disk florets more numerous,
whitish; seeds small, flat, grayish with whitish margins. The whole
plant has a characteristic sage-like odour which is offensive to
some people but attractive to others. Flowers from June to late
autumn.
Habitat: Yarrow is very common throughout
Ontario in natural areas, meadows, pastures, waste places, roadsides,
and frequently in lawns.
Related Links
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... on weed identification, order OMAFRA
Publication 505: Ontario Weeds
... on weed control, order OMAFRA
Publication 75: Guide To Weed Control
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