A rhizomatous perennial characteristically found in mesotrophic or meso-eutrophic, acidic or neutral standing waters in lakes, ponds and flooded mineral workings, or in canals and the backwaters of rivers. It may, however, occupy a broader habitat range in areas such as N. Ireland where it is especially frequent. It fruits freely, and also reproduces by turions. 0-480 m (Angle Tarn, Patterdale, Westmorland).
Although P. obtusifolius is better recorded than in the 1962 Atlas, the map suggests that it has declined throughout much of its British range. There is less evidence of decline in Ireland.
Circumpolar Boreo-temperate element, with a disjunct distribution.
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Light (Ellenberg): 7
Moisture (Ellenberg): 12
Reaction (Ellenberg): 6
Nitrogen (Ellenberg): 5
Salt Tolerance (Ellenberg): 0
January Mean Temperature (Celsius): 3.4
July Mean Temperature (Celsius): 14.7
Annual Precipitation (mm): 994
Perennation - primary
Life Form - primary
Clonality - primary
Count of 10km squares in Great Britain: 601
Count of 10km squares in Ireland: 155
Count of 10km squares in the Channel Isles: 0
Atlas Change Index: 0.96
Atlas text references
1986. Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
1965. Vergleichende Chorologie der zentraleuropäischen Flora. Volume 1. 2 vols.
1995. Pondweeds of Great Britain and Ireland. Botanical Society of the British Isles Handbook no. 8.
1997. Aquatic plants in Britain and Ireland.