This rhizomatous perennial has a very narrow habitat range, being confined to shallow, species-rich drainage ditches in lowland grazing marshes, where it typically grows in calcareous, mesotrophic or meso-eutrophic water. Although it fruits relatively freely and also produces turions, it shows little or no propensity to colonise new habitats. Lowland.
P. acutifolius appears to be in gradual, long-term decline. Since 1960 it has decreased in Norfolk and become extinct in the London area and critically endangered in Dorset. However, several vigorous populations survive in Sussex.
European Temperate element.
Perennation - primary
Life Form - primary
Clonality - primary
Count of 10km squares in Great Britain: 35
Count of 10km squares in Ireland: 0
Count of 10km squares in the Channel Isles: 0
Atlas Change Index: 0.05
RDB Species Accounts
Potamogeton acutifolius Link (Potamogetonaceae)
Sharp-leaved pondweed, Dyfrllys Meinddail
Status in Britain: VULNERABLE.
Status in Europe: Not threatened.
P. acutifolius has a narrower habitat range than most aquatics in Britain, as it is virtually restricted to shallow, species-rich drainage ditches in lowland grazing marshes. It is found in calcareous, mesotrophic or meso-eutrophic water, where typical associates include Elodea canadensis, Hottonia palustris, Hydrocharis morsus-ranae, Lemna minor, L. trisulca, Myriophyllum verticillatum, Potamogeton natans, Ranunculus circinatus, Sagittaria sagittifolia and Spirodela polyrhiza. It is also recorded from a pond in Middlesex and there are single records from the Hereford & Gloucester and Oxford Canals. There is, however, no evidence that this species ever became established in the canal system, nor is it known from other newly available habitats such as gravel pits.
P. acutifolius flowers and fruits more freely than some other linear-leaved pondweeds, including the closely related P. compressus. Turions are apparently produced in smaller quantity than in some other species, but they can usually be found from August onwards. The life history and reproduction of the species require detailed study.
There has been a substantial decline. It has not been seen in Yorkshire and Lincolnshire since the late 17th century. It was last seen in Essex in 1700, Herefordshire in 1846, Warwickshire in c. 1859, Gloucestershire in 1870, Hampshire in 1898 and Northamptonshire in 1910. In many of these counties the only evidence for its occurrence is a single herbarium specimen. It may be extinct in Surrey, where it was last seen in 1965, and if it still survives at its sole site in Middlesex it does so very precariously. Although it persists in the Wareham area, its distribution there has contracted since the last century and it now occurs in small quantity in one small area; it has also been lost from some of its sites in Norfolk. The reasons for the decline appear to be habitat destruction, the conversion of grazing marshes for arable use, and eutrophication. The headquarters of this species are now in Sussex, where it occurs in abundance at Amberley Wild Brooks and has also been recorded recently at other localities. In Norfolk it has been successfully introduced to the RSPB reserve at Strumpshaw.
P. acutifolius has a restricted world distribution, being confined to temperate regions of Europe. It is found from southern Sweden southwards to France, Italy and the Balkans, but it is absent from the Mediterranean region.
C. D. Preston, adapted from an account in Preston & Croft (1997)
PLANTATT - Attributes of British and Irish plants. (.zip 1455KB) This dataset was compiled and published in 2004, and last updated in November 2008. Download includes an Excel spreadsheet of the attributes, and a PDF explaining the background and nomenclature. Note that the PDF version is the booklet as published, whereas the Excel spreadsheet incorporates subsequent corrections. A hardcopy can be purchased from the Centre for Ecology and Hydrology.
Atlas text references
1986. Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
1995. Pondweeds of Great Britain and Ireland. Botanical Society of the British Isles Handbook no. 8.
1997. Aquatic plants in Britain and Ireland.
Preston & Pearman (1998b)
1999. British Red Data Books. 1. Vascular plants, edn 3.