An annual of open ground on a wide range of soils, particularly those which are rich in nutrients. It is found by ponds, lakes, streams and ditches, in waste places, on roadsides and railways, and is sometimes a pestilential weed of cultivated land. Mainly lowland, but ascending to at least 450 m near Garrigill (Cumberland) and in Clun Forest (Salop).
The overall distribution of this species is stable since the 1962 Atlas, although there have been some losses at the northern edge of its range.
Eurasian Temperate element, but naturalised in N. America so distribution is now Circumpolar Temperate.
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Light (Ellenberg): 7
Moisture (Ellenberg): 6
Reaction (Ellenberg): 6
Nitrogen (Ellenberg): 7
Salt Tolerance (Ellenberg): 0
January Mean Temperature (Celsius): 3.6
July Mean Temperature (Celsius): 14.6
Annual Precipitation (mm): 1077
Height (cm): 80
Perennation - primary
Life Form - primary
Clonality - primary
Count of 10km squares in Great Britain: 2578
Count of 10km squares in Ireland: 934
Count of 10km squares in the Channel Isles: 12
Atlas Change Index: -0.95
Weighted Changed Factor: -12
Weighted Change Factor Confidence (90%)
Atlas text references
1988. Comparative Plant Ecology.
1986. Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
Jalas & Suominen (1979)
1981. Docks and knotweeds of the British Isles. Botanical Society of the British Isles Handbook no. 3.
1945. Biological Flora of the British Isles. No. 14. Polygonum L. em. Gaertn. (pp. 117-120), Polygonum persicaria L. (pp. 121-131), Polygonum lapathifolium L. (P. tomentosum Schr. of many continental authors) (pp. 121-131), Polygonum petecticale (Stokes) Druce (P. maculatum Trimen & Dyer, P. nodosum Persoon, etc) (pp. 140-143). Journal of Ecology. 33:117-143.