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.
This species is now known to be much more frequent than was apparent in the 1962 Atlas. This is almost certainly attributable to more detailed recording of aquatic habitats.
European Temperate element.
Height (cm): 5
Perennation - primary
Perennation - secondary
Life Form - primary
Life Form - secondary
Comment on Life Form
Clonality - primary
Clonality - secondary
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
Scarce Atlas Account
Elatine hexandra (Lapierre) DC.
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 of north European vascular plants north of the Tropic of Cancer. 3 vols,
, Königstein, (1986)
Vergleichende Chorologie der zentraleuropäischen Flora. Volume 2. 2 vols,
, Jena, (1978)
Aquatic plants in Britain and Ireland,
, Colchester, (1997)
Scarce plants in Britain,
, Peterborough, (1994)