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Ministry of Agriculture, Food and Rural Affairs

Perennial sow-thistle

Scientific Name: Sonchus arvensis

Other Names: laiteron des champs, creeping sow-thistle, field sow-thistle, glandular-hairy perennial sow-thistle

Family: Composite or Aster family (Compositae)

General Description: Perennial sow-thistle is a perennial weed reproducing by seed and by buds on underground roots.

Habitat : Perennial sow-thistle occurs throughout Ontario in cultivated fields, pastures, meadows, woodland, waste places, roadsides, gardens and occasionally in lawns.


  • Leaves are broadly club-shaped
  • Leaves have irregularly toothed margins with prickles at the end


  • Stems are erect
  • Reaching a height of 60-150 cm
  • Smooth and hairless on the lower part but glandular-hairy towards the top and on branches
  • Each hair has a tiny gland at its tip


  • Leaves are alternate (1 per node)
  • Leaves are variable in shape
  • Lower leaves are lobed and irregularly toothed
  • Middle and upper leaves are similar but have shorter stalks and clasp the stem
  • Uppermost leaves are small and narrow, have no lobes and very few teeth

Flowers and Fruit

  • Flower heads are bright yellow and 2.5 – 4 cm in diameter
  • Each flower head has strap-shaped ray florets
  • Flowers from June to late autumn  

Often Confused With / Distinguishing Features
The perennial sow-thistle is often confused with several weeds. The hairs with glands on its tips do not occur in smooth perennial sow-thistle which is often confused with perennial sow-thistle. It is also commonly mistaken for annual sow-thistle, spiny annual sow-thistle and dandelion.

Herbicide Resistance
No documented cases of herbicide resistance to date.



Perennial sow-thistle seedling at the 2-leaf stage Perennial sow-thistle leaf Perennial sow-thistle before flowering Perennial sow-thistle flower head Perennial sow-thistle plantClick to enlarge.