A prostrate annual, biennial or short-lived perennial of sand, shingle or shell beaches, sometimes found on other open sandy ground near the sea, usually just above the limit of the highest tides. Lowland.
There are now many more records for this species than in the 1962 Atlas, not only in N. England and Scotland, where it was patently under-recorded, but also Cornwall, Hampshire and Wales. Like other strand-line species, its numbers often fluctuate annually. Most populations are subsp. raii. Subsp. oxyspermum has been reported as a casual in Scotland, perhaps having arrived naturally from the Baltic region.
European Wide-temperate element; also in N. America.
Light (Ellenberg): 9
Moisture (Ellenberg): 6
Reaction (Ellenberg): 7
Nitrogen (Ellenberg): 8
Salt Tolerance (Ellenberg): 3
January Mean Temperature (Celsius): 4.6
July Mean Temperature (Celsius): 14.8
Annual Precipitation (mm): 1102
Height (cm): 20
Perennation - primary
Life Form - primary
Clonality - primary
Count of 10km squares in Great Britain: 305
Count of 10km squares in Ireland: 75
Count of 10km squares in the Channel Isles: 9
Atlas Change Index: 0.01
Scarce Atlas Account
Polygonum oxyspermum C. Meyer & Bunge ex Ledeb.
Status: not scarce
This is a characteristic but local plant of strandlines on coastal sand, shingle and silty mud. Associated species include Atriplex glabriuscula, A. laciniata, Cakile maritima and Salsola kali. It also occurs above the strandline in embryonic foredunes.
It is an annual or short-lived perennial and is probably largely self-pollinated. It flowers from July to October.
This species has declined in some areas. It has always been rare in eastern England. Strandline plants are notoriously erratic in appearance (Webb & Akeroyd 1991), so disappearance from a particular locality does not always imply a decline. Nevertheless, this plant has suffered from the increased disturbance of many beaches, with consequent damage to strandline and foredune communities. It may be under-recorded on the west coast of Scotland.
The species occurs along most of the coasts of Europe, except southern and western Spain (Jalas & Suominen 1979). Subsp. raii extends from north-western Spain to arctic Russia, with almost indistinguishable plants from the coasts of the Black Sea having been called P. mesembricum. Subsp. oxyspermum, with longer, more greenish-brown fruits than subsp. raii, occurs in the Baltic and southern Norway. Longer-lived perennial plants from the western and central Mediterranean coasts belong to subsp. robertii (an epithet erroneously ascribed to British material in the past).
The British plant is subsp. raii (Bab.) D. Webb & Chater. Some plants from Scotland, especially from Arran, are close to subsp. oxyspermum and require further investigation.
J. R. Akeroyd
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.
1962. The taxonomy of Polygonum aviculare and its allies in Britain. Watsonia. 5:177-214.