Ceratophyllum demersum

Tracheophyta MagnoliopsidaCeratophyllaceaeCeratophyllumCeratophyllum demersum


An aquatic which grows submerged in still or slowly flowing, eutrophic water in lakes, ponds, rivers, canals and ditches. It may be so abundant in ponds and ditches that it forms dense masses which rise above the water surface. Reproduction is mostly by vegetative fragmentation, but seeds are produced in still-water habitats in some years. Lowland.



World Distribution

Circumpolar Southern-temperate element.

© G. Toone, IWNHAS

Broad Habitats

Standing water and canals

Light (Ellenberg): 7

Moisture (Ellenberg): 12

Reaction (Ellenberg): 7

Nitrogen (Ellenberg): 7


Salt Tolerance (Ellenberg): 1

January Mean Temperature (Celsius): 3.7

July Mean Temperature (Celsius): 15.8

Annual Precipitation (mm): 770

Length: 100

Perennation - primary


Life Form - primary

Perennial hydrophyte (perennial water plant)



Clonality - primary

Irregularly fragmenting (mainly water plants)

Distribution information

Count of 10km squares in Great Britain: 927

Count of 10km squares in Ireland: 62

Count of 10km squares in the Channel Isles: 1

Atlas Change Index: 0.87

Weighted Changed Factor: 20

Weighted Change Factor Confidence (90%)


Distribution information

JNCC Designations


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

Atlas (28a)
Hultén E, Fries M
1986.  Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
Jalas & Suominen (1989)
Preston CD, Croft JM
1997.  Aquatic plants in Britain and Ireland.