An annual of wet places growing beside ponds, lakes and rivers and in shallow ditches, damp hollows in fields, cattle-trampled places in pasture and abandoned peat cuttings. It grows in nutrient-rich soils, but appears indifferent to soil reaction. Lowland.
P. mitis has been confused with P. hydropiper and P. minor, making interpretation of the map difficult. It is now known from many more 10-km squares since the 1962 Atlas. In Britain, however, populations have been lost through the regulation of water levels, the fencing of ditches, and the filling in of ponds. Webb (1984) suggests that this species is a recent introduction to Ireland.
European Temperate element.
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Light (Ellenberg): 7
Moisture (Ellenberg): 8
Reaction (Ellenberg): 6
Nitrogen (Ellenberg): 9
Salt Tolerance (Ellenberg): 0
January Mean Temperature (Celsius): 3.8
July Mean Temperature (Celsius): 15.9
Annual Precipitation (mm): 780
Height (cm): 75
Perennation - primary
Life Form - primary
Clonality - primary
Count of 10km squares in Great Britain: 203
Count of 10km squares in Ireland: 31
Count of 10km squares in the Channel Isles: 1
Atlas Change Index: -0.9
Scarce Atlas Account
NOTE: The account below is for the sub-species. Closely related species and sub-species may have separate accounts listed elsewhere in the Online New Atlas
Persicaria laxiflora (Weihe) Opiz
Together with its close relative P. minor, and the docks Rumex maritimus and R. palustris, P. laxiflora is typical of a distinctive community on wet muds or peat banks, left exposed in late summer as the water level drops. This open vegetation develops by ditches, in wet hollows, by cattle-trampled patches in pastures, by ponds and near former middens. In some areas, it is typical of abandoned peat-cuttings. It grows on wet or damp soils, rich in nutrients, but with no particular preference for soil reaction. The sites are well-illuminated and strictly lowland.
P. laxiflora is an annual, flowering in late summer, and reproducing entirely by seed.
P. laxiflora has frequently been confused with forms of P. hydropiper, as well as P. minor, such that trends in distribution can only be suggested with caution. However, it has apparently declined throughout England and Wales, probably as a result of closer regulation of water levels, elimination of ponds and fencing of ditches. All these factors contribute to the decrease of wet mud habitats.
P. laxiflora is widespread in Europe between 40 °N and 55 °N, but is rare in the north and in the Mediterranean region (Jalas & Suominen 1979). It has been reported from western Asia but the eastern limit of its range is uncertain because it has often been confused with other species.
J. O. Mountford
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.
1994. Scarce plants in Britain.