Damasonium alisma

Tracheophyta MagnoliopsidaAlismataceaeDamasoniumDamasonium alisma


This annual grows on acidic mud by small ponds where the habitat is kept open by fluctuating water levels and disturbance by grazing animals. Its sites are usually flooded in winter but may be wet or dry in summer. The seeds appear to persist in a long-lived seed bank. Lowland.



World Distribution

Mediterranean-Atlantic element.

Broad Habitats

Standing water and canals

Light (Ellenberg): 8

Moisture (Ellenberg): 10

Reaction (Ellenberg): 5

Nitrogen (Ellenberg): 3


Salt Tolerance (Ellenberg): 0

January Mean Temperature (Celsius): 3.9

July Mean Temperature (Celsius): 16.5

Annual Precipitation (mm): 707

Life form information

Height (cm): 30

Perennation - primary


Life Form - primary

Annual hydrophyte (aquatic therophyte)



Clonality - primary

Little or no vegetative spread

Count of 10km squares in Great Britain: 54

Count of 10km squares in Ireland: 0

Count of 10km squares in the Channel Isles: 0

Atlas Change Index: -0.52

Distribution information

Plantatt Conservation Status


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 (301d)
Marren PR
1999.  Britain's rare flowers.
Preston CD, Croft JM
1997.  Aquatic plants in Britain and Ireland.
Wigginton MJ
1999.  British Red Data Books. 1. Vascular plants, edn 3.