Limosella aquatica

Tracheophyta MagnoliopsidaScrophulariaceaeLimosellaLimosella aquatica

Ecology

An annual of the muddy edges of rivers, lakes, reservoirs, pools, ditches, rutted tracks and roadsides. In the Burren (Co. Clare) it also occurs in limestone solution hollows. It may prefer mildly acidic, nutrient enriched soils. Plants reproduce by seed and also spread by stolons. 0-455 m (Malham Moor, Mid-W. Yorks.).

Status

Native

World Distribution

Circumpolar Boreo-temperate element.

Broad Habitats

Standing water and canals

Light (Ellenberg): 8

Moisture (Ellenberg): 8

Reaction (Ellenberg): 5

Nitrogen (Ellenberg): 5

0

Salt Tolerance (Ellenberg): 0

January Mean Temperature (Celsius): 3.5

July Mean Temperature (Celsius): 15.5

Annual Precipitation (mm): 858

Life form information

Height (cm): 6

Perennation - primary

Annual

Life Form - primary

Therophyte (annual land plant)

Woodiness

Herbaceous

Clonality - primary

Far-creeping by stolons in illuminated medium

Count of 10km squares in Great Britain: 223

Count of 10km squares in Ireland: 13

Count of 10km squares in the Channel Isles: 0

Atlas Change Index: 1

Distribution information

JNCC Designations

NBNSYS0000004089

Scarce Atlas Account

Scarce Atlas Account: 

Limosella aquatica L.

Mudwort

Status: scarce

 

 

L. aquatica grows on exposed mud at the edges of rivers, lakes, reservoirs, pools, ditches and winter-flooded ruts in tracks and unmetalled roads. It may be mildly calcifuge - many of its sites were on acidic soils on commons - and is perhaps favoured by nutrient enrichment from animal droppings. It is often found with other annual species, including Eleocharis acicularis, Gnaphalium uliginosum, Juncus bufonius and Rorippa palustris, and with stranded aquatics such as Myriophyllum alterniflorum or species of Ranunculus, It occurs in bare areas on saltmarshes in Hampshire. It is a predominantly lowland species, ascending to 450 metres on Malham Moor.

The species is an ephemeral which germinates very rapidly when mud becomes exposed in the summer and completes its life-cycle before the autumn. Populations vary greatly in size from year to year, and can be very large in those seasons when water levels are low. It has often been recorded at sites after an apparent absence of many years. Dry seeds yielded only 0.8% germination after 27 months (Salisbury 1970) but a greater proportion may remain viable in wet mud. For further details of the reproductive biology of this species, see Salisbury (1967).

L. aquatica is erratic in its appearance, and certainly could not have been found in any one year in all the 10 km squares for which there are pre-1970 records. Nevertheless, like several annuals of exposed mud in small pools, it has undoubtedly suffered a major decline in England and Wales (Salisbury 1970). The reasons for this probably include the surfacing of roads; the drainage of ‘splashy places by the roadside’ (Townsend 1883) and other ephemeral pools; and the fact that many ponds have dried out completely, become overgrown following the cessation of grazing or been engulfed by urban development. Lousley (1976) stresses the former role in Surrey of ducks and geese in creating muddy, nutrient-enriched areas around pools. The sites where the plant has survived tend to be larger waters rather than the small sites which were formerly its most characteristic habitat. It has, however, colonised some newly created habitats such as ‘scrapes’ dug for birds and the margins of gravel pits. In Scotland L. aquatica has been recorded with increasing frequency since 1950 (Leach, Stewart & Ballantyne 1984), probably because this inconspicuous species had been overlooked previously. 

It is widespread in northern Europe, with scattered colonies in the mountains further south. It has a circumboreal distribution.

 

 

C. D. Preston

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 (226d)
Curtis TGF, McGough HN
1988.  The Irish Red Data Book. 1. Vascular Plants.
Hultén E, Fries M
1986.  Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
Meusel H, Jäger E, Rauschert S, Weinert E
1978.  Vergleichende Chorologie der zentraleuropäischen Flora. Volume 2. 2 vols.
Stewart A, Pearman DA, Preston CD
1994.  Scarce plants in Britain.