Elatine hexandra

Tracheophyta MagnoliopsidaElatinaceaeElatineElatine hexandra

Ecology

E. hexandra grows as an annual on exposed mud at the edge of lakes, reservoirs, ponds and flooded gravel-pits, or submerged on open substrates in shallow, oligotrophic to eutrophic water. When submerged it may sometimes persist as a short-lived perennial. Like many species in this habitat, it is subject to large annual fluctuations in numbers. 0-440 m (Lake Ferta, N. Kerry), and reportedly to 490 m in the Scottish Highlands.

Status

Native

World Distribution

European Temperate element.

Broad Habitats

Standing water and canals

Light (Ellenberg): 7

Moisture (Ellenberg): 10

Reaction (Ellenberg): 5

Nitrogen (Ellenberg): 4

0

Salt Tolerance (Ellenberg): 0

January Mean Temperature (Celsius): 3.7

July Mean Temperature (Celsius): 14.2

Annual Precipitation (mm): 1365

Life form information

Height (cm): 5

Length: 10

Perennation - primary

Annual

Perennation - secondary

Perennial

Life Form - primary

Annual hydrophyte (aquatic therophyte)

Life Form - secondary

Perennial hydrophyte (perennial water plant)

Comment on Life Form

According to Stace (1991) it can live for several years submerged without flowering

Woodiness

Herbaceous

Clonality - primary

Little or no vegetative spread

Clonality - secondary

Shortly creeping and rooting at nodes

Count of 10km squares in Great Britain: 212

Count of 10km squares in Ireland: 79

Count of 10km squares in the Channel Isles: 3

Atlas Change Index: 1.07

Distribution information

JNCC Designations

NBNSYS0000002983

Scarce Atlas Account

Scarce Atlas Account: 

Elatine hexandra (Lapierre) DC.

Six-stamened waterwort

Status: scarce

 

This is an aquatic plant, often behaving as an ephemeral on exposed, wet mud. Plants may persist in the vegetative state at depths of 1 metre or more, where, even if noticed, they may be mis-recorded as young Callitriche spp. When exposed during summer droughts, E. hexandra can dominate substantial areas. It tolerates a wide range of nutrient conditions and substrata, preferring soft, sandy or peaty mud, but can occur on almost pure sand or even some types of fine gravel. Occasionally it can occur on peat at the edges of moorland lakes. It often occurs in moderately nutrient rich water and can even persist in shallow water at the edges of highly turbid eutrophic water bodies which receive substantial amounts of fertiliser run-off. A common associate of submerged plants is Eleocharis acicularis, and other associates in shallow water or on mud may include its rarer relative E. hydropiper, Littorella uniflora and Subularia aquatica. Peatier sites will normally have Baldellia ranunculoides and Juncus bulbosus. It grows predominantly in the lowlands, ascending to 425 metres at Llyn Gynon; a record from nearly 500 metres in the Scottish Highlands (Hooker 1884) has not been localised.

It is an annual to short-lived perennial, capable of flowering in shallow water but showing rapid germination, maturation, and abundant seed-set, on seasonally exposed mud. Limited vegetative spread is possible, but reproduction is apparently mainly by seed, with replenishment of the seed bank in drought years. Populations may fluctuate considerably from one year to the next.

Although suffering local loss of habitat and apparent decline in the south of its range, E. hexandra does not appear to be generally under threat. It is better known to botanists than in the past and is consequently being discovered at new sites. It is still apparently under-recorded.

It is widespread in Europe, extending north to southern Scandinavia, and also occurs in North and West Africa.

 

A. J. Silverside

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 (61c)
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.
Preston CD, Croft JM
1997.  Aquatic plants in Britain and Ireland.
Stewart A, Pearman DA, Preston CD
1994.  Scarce plants in Britain.