Information on Bog Pondweed

Common Name: Bog Pondweed
Scientific Name: Potamogeton polygonifolius
Irish Name: Liach mhóna
Family Group: Potamogetonaceae
Distribution: View Map (Courtesy of the BSBI)
Flowering Period


Click for list of all flowering by month
Bog Pondweed is not easily confused with other wild plants on this web site.


Most commonly found in still or slow-moving acid peaty waters, this species can be quite variable. It has stalked, floating, lanceolate-oval leaves which have opaque veins.  It can also have submerged leaves with long stems and narrow blades. The flowers are very small, greenish with 4 tepals and 4 stamens and separate carpels. They are borne in spikes which emerge from the leaf axils and are held clear of the water. Some species have a flexible joint below the leaf but this species does not. They flower from May to September and are perennial natives, this species being widespread within its habitat. It belongs to the Potamogetonaceae family. 

I first saw this species on the Inishowen peninsula in Co Donegal in late June, 2015 when I also photographed it. 

If you are satisfied you have correctly identified this plant, please submit your sighting to the National Biodiversity Data Centre

Pondweed, Bog
Pondweed, Bog

Pondweeds are very difficult to identify and there are more than fifteen species (plus more subspecies) growing in Ireland. I would never have been able to identify it and am very grateful to Paul Green, BSBI Vice-County Recorder for Waterford and Wexford for his help.