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Perennial Sow-Thistle

Perennial Sow-Thistle

Sonchus arvensis

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

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How common: Very common

Perennial Sow-Thistle is a tall, long‑lived plant with bright yellow, dandelion‑like flower heads. You see it on fields, waste ground, roadsides and seashores, often forming big patches. Its deep, creeping roots help it spread widely and come back year after year.

Did you know?

  • If you break the stem or leaf, it oozes white milky sap.
  • It spreads both by wind‑blown seeds and by long underground roots, which makes it a stubborn weed in fields.

About the species

Identification

Usually 50–150 cm. Stems hollow, mostly unbranched, smooth below, sometimes with tiny yellowish bumps near the top and behind the flower heads. Leaves bluish‑green; lower ones have a stalk, upper ones wrap around the stem with ear‑like lobes. Edges are toothed to deeply cut with soft prickles; surfaces smooth. Loose clusters of long‑stalked yellow flower heads, each about 4–5 cm across. Breaks ooze white milky sap. Flat brown seeds have a silky tuft. Unlike dandelion, it has many heads and leaves on the stem; typically taller and bluer than Common Sow‑thistle. Flowers in Finland from July to September.

Plant group

Herbaceous plants

Habitat

yards and roadsides, shore

Flowering

Jul–Sep

About the habitat

Open, disturbed places such as fields, fallow ground, gardens, road verges and shores; grows on clay, loam or sandy soils. Common in southern and central Finland, rare in Lapland.

Sources

Photo: Krzysztof Ziarnek, Kenraiz, CC BY-SA 4.0 https://commons.wikimedia.org/wiki/File:Sonchus arvensis kz08.jpg

Text: Pinkka: Verso- ja leviäintunnistus - Kaikki leviäimet, CC BY 4.0 https://laji.fi/taxon/MX.39936

Text: Pinkka: Verso- ja leviäintunnistus - Kaikki versot, CC BY 4.0 https://laji.fi/taxon/MX.39936

Text: Pinkka: Laaja maatalouslajintuntemus 4 op - Koppisiemeniset, CC BY 4.0 https://laji.fi/taxon/MX.39936

Text: Pinkka (Luomus), CC BY 4.0 https://laji.fi/taxon/MX.39936

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

See also