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Curlytop Knotweed

Curlytop Knotweed

Persicaria lapathifolia

Identify the Curlytop Knotweed from a photo and log your finds with Florapass.

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How common: Common

Curlytop Knotweed is a fast-growing annual knotweed seen in disturbed, often moist places. It has narrow leaves that often show a big dark blotch, and dense, upright clusters of tiny pale pink to yellowish flowers. You can notice a thin papery sleeve around the stem at each leaf base. It is widespread across the northern parts of the world in fields, shores and waste ground.

Did you know?

  • It has two subspecies: one common on shores with pinkish stems and flowers, and a paler one typical of arable land.
  • The thin papery sleeve at each leaf base is a telltale feature of the knotweed family.

About the species

Identification

An annual, upright or leaning plant 10–80 cm tall. Stems are few-branched, sometimes swollen at the joints. Leaves on short stalks, narrow oval, 4–15 cm, smooth above, sometimes hairy below, often with a big dark blotch in the center. At each leaf base is a thin, papery sleeve around the stem; its rim is smooth or with only tiny hairs. Flower clusters are dense, upright and thick, with many very small pale pink to yellowish flowers. Seeds are small, shiny, brown to black, flattened (about 2–3 mm). Can be confused with Redshank, which has a long bristly fringe on the sleeve. Flowers in Finland from July to September.

Plant group

Herbaceous plants

Habitat

yards and roadsides

Flowering

Jul–Sep

About the habitat

Grows on fields, shores, ditches, waste ground, roadsides and tips, especially on moist, nutrient-rich, disturbed soil. Can form dense stands. Common throughout the country, rare in Lapland.

Sources

Photo: Linda Jo Conn, CC BY 4.0 https://www.gbif.org/occurrence/5938468277

Text: Pinkka: Verso- ja leviäintunnistus - Kaikki leviäimet, CC BY 4.0 https://laji.fi/taxon/MX.38225

Text: Pinkka: Verso- ja leviäintunnistus - Kaikki versot, CC BY 4.0 https://laji.fi/taxon/MX.38225

Text: Pinkka: Laaja maatalouslajintuntemus 4 op - Koppisiemeniset, CC BY 4.0 https://laji.fi/taxon/MX.38225

Text: Pinkka (Luomus), CC BY 4.0 https://laji.fi/taxon/MX.38225

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

See also