A perennial herb of base-poor soils in damp pastures, hay meadows and river-banks, in tall-herb communities in river valleys and on mountain ledges and roadsides. Many colonies originate as garden escapes or throw-outs. 0-430 m above Garrigill (Cumberland).
The native range of P. bistorta is now largely obscured by alien occurrences, and all records are mapped as if they are native. It was lost from many sites in S. England and Ireland before 1930. Although now better recorded than in the 1962 Atlas, its overall range is stable.
Eurasian Boreo-temperate element, in N. America native in west and naturalised in east so now Circumpolar Boreo-temperate.
Light (Ellenberg): 6
Moisture (Ellenberg): 7
Reaction (Ellenberg): 6
Nitrogen (Ellenberg): 6
Salt Tolerance (Ellenberg): 0
January Mean Temperature (Celsius): 3.3
July Mean Temperature (Celsius): 14.8
Annual Precipitation (mm): 1021
Height (cm): 80
Perennation - primary
Life Form - primary
Clonality - primary
Count of 10km squares in Great Britain: 1355
Count of 10km squares in Ireland: 43
Count of 10km squares in the Channel Isles: 0
Atlas Change Index: -0.44
Weighted Changed Factor: -18
Weighted Change Factor Confidence (90%)
Atlas text references
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.
1996. Flora Britannica.
1965. Vergleichende Chorologie der zentraleuropäischen Flora. Volume 1. 2 vols.