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)

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%)


JNCC Designations


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.