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.

Annual Sow-thistle A. Lower stem leaf.

Annual Sow-thistle B. Upper leaf.

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.

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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