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Prickly Sow-Thistle

Prickly Sow-Thistle

Sonchus asper

Identify the Prickly Sow-Thistle from a photo and log your finds with Florapass.

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How common: Very common

Alien species

Prickly Sow-Thistle is an upright annual of the daisy family with pale yellow, dandelion-like flower heads and shiny, spiny-edged leaves. It is a familiar weed of disturbed places around settlements—waste ground, gardens, fields and roadsides. Break a stem and it oozes white milky sap.

Did you know?

  • Broken stems ooze white milky sap.
  • The small flat seeds have silky hairs and are blown away like dandelion clocks.

About the species

Identification

Upright annual 30–80 cm tall. Stem leafy, hollow and full of white sap; large plants may branch. Leaves shiny dark green, stiff, with sharp-looking but fairly soft prickly teeth. Lower leaves have a short stalk; upper leaves wrap around the stem with a heart-shaped base and rounded lobes. Clusters of many small, pale yellow, dandelion-like heads, each about 1.5–2 cm across. Later, flat brown seeds carry a white silky tuft and drift on the wind. Compared with Common Sow-thistle, the leaves are shinier, stiffer and less deeply cut. Flowers in Finland from July to September.

Plant group

Herbaceous plants

Habitat

yards and roadsides

Flowering

Jul–Sep

About the habitat

A long-time companion of people, it grows on disturbed, open ground such as waste places, gardens, fields, roadsides, walls and ports. It favours warm, sandy, nutrient-rich soil. Common in southern Finland, becoming scarcer northwards; an old, established introduction. Very rare in Lapland.

Sources

Photo: Anne Parsons, CC0 1.0 https://www.gbif.org/occurrence/5938312379

Text: Pinkka: Verso- ja leviäintunnistus - Kaikki versot, CC BY 4.0 https://laji.fi/taxon/MX.39930

Text: Pinkka: Maatalouslajintuntemus - Asteraceae, CC BY 4.0 https://laji.fi/taxon/MX.39930

Text: Pinkka: Verso- ja leviäintunnistus - Kaikki leviäimet, CC BY 4.0 https://laji.fi/taxon/MX.39930

Text: Wikipedia (Finnish), CC BY-SA 4.0 https://fi.wikipedia.org/wiki/Otavalvatti

See also