Ontario Weeds: Annual sow-thistle

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

Name: Annual sow-thistle, Sonchus oleraceus L.

Other Names: Laiteron potager, Common annual sow-thistle, laiteron lisse, laiteron commun.

Family: Composite or Aster Family (Compositae) 

General Description: Very similar to Spiny annual sow-thistle in general appearance.

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Annual Sow-thistle A. Lower stem leaf.

Annual Sow-thistle B. Upper leaf.

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Stems & Roots: The part of the leaf closer to the stem very narrow; the base of the leaf clasping the stem with 2 angular or pointed lobes; all margins with small teeth and soft weak spines; and seed ridged lengthwise but each ridge with numerous small cross-wrinkles.

Flowers & Fruit: Seed ridged lengthwise but each ridge with numerous small cross-wrinkles.

Habitat: It occurs in habitats similar to those of Spiny annual sow-thistle.

Similar Species: Easily distinguished by having leaves which are deeply lobed with the terminal lobe being short, broad and rounded or triangular.

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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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