Ontario Weeds: Tansy

Table of Contents

1. Name
2. Other Names
3. Family
4. General Description
   • Photos and Pictures
5. Stems and Roots
6. Flowers and Fruit
7. Habitat
8. Similar Species
9. Related Links

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Photos and Pictures

Tansy.

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Stems & Roots: Stems coarse, erect, tall (40-150cm, 16-60in.), hairless; leaves pinnately divided and redivided, at first resembling leaves of Yarrow but becoming larger and coarser with the ultimate divisions not as fine; basal leaves large and long-stalked, often forming large dense clumps; stem leaves numerous, smaller and stalkless towards the top, alternate (1 per node);

Flowers & Fruit: Flower heads in dense, rounded or flat-topped clusters at ends of stems and branches; each head firm, button-like, 5-10mm (1/5-2/5in.) across, without ray florets but with numerous, small, densely packed yellow disk florets. All parts of the plant have a strong, characteristic "tansy" aroma. Flowers from July to September.

Habitat: Tansy occurs sporadically throughout Ontario in waste places, edges of fields, roadsides and old gardens.

Similar Species: It is distinguished by its large, pinnately divided and redivided leaves which resemble but are coarser than Yarrow, its small button-like yellow flower heads crowded in rounded or flat-topped clusters, and its characteristic aroma.

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Related Links

... on general Weed topics
... on weed identification, order OMAFRA Publication 505: Ontario Weeds
... on weed control, order OMAFRA Publication 75: Guide To Weed Control

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