A slender aquatic perennial, with long-stalked elliptical floating leaves. The flowers are about 15mm across, with 3 white petals each with a yellow spot. Found in canals and other quiet waters.
Action Plan Summary
The distribution of this plant is localised in the UK, with records from Wales, the West Midlands, northern England and Scotland. According to data published on the Biodiversity Action Reporting System (BARS) as part of the 2008 Defra reporting round, Luronium natans was recorded from 55 sites in the UK (18 in England; 36 in Wales; and one in Scotland).
L. natans continues to be discovered in new, previously overlooked sites. With improved understanding of the species' habitat and ecological requirements, many previously overlooked populations have been found, especially in the upland part of its range. A recent national assessment of the available data by Lockton (2008) has suggested that the total number of extant sites is increasing.
Floating water-plantain is one of the most highly protected plant species in Britain. It is listed on Annexes II and IV of the Habitats Directive and protected under Schedule 4 of the Conservation (Natural Habitats, etc.) Regulations 1994 and Schedule 8 of the Wildlife and Countryside Act 1981.
- L. natans has been recorded from the Potter Heigham area since the 1950s, and this is currently the only known site of the species in the county. L. natans was also recorded from Calthorpe Broad in the 1970s, but there have been no recent records. Although the occurrence of the species at both sites is often believed to be the result of introductions, there is little direct evidence for this.
- Although the Potter Heigham population was stable for many years, baseline surveys commissioned by Broadland Environmental Services Ltd (BESL) in 2007 as part of the Broadland Flood Alleviation Project (BFAP) failed to find the species at its recorded location. Further BFAP surveys in June 2008 found three populations in two dykes.
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Current factors causing loss or decline in Norfolk
The threats to this species in the Broads include:
- Intensive dyke maintenance;
- Lack of channel management; and
- Poor water quality.
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Current Action in Norfolk
- The Broads population has been monitored over the years by a number of organisations, including Natural England, the Natural History Museum in Norwich and Broadland Environmental Services Ltd (BESL).
- A translocation experiment was undertaken in the past but proved to be unsuccessful.
- The Potter Heigham site is being managed under an ESA agreement. Natural England has provided detailed management advice to the landowner.
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Action Plan Objectives and Targets
- Maintain the current range of this species in the UK.
- By 2010, increase connectivity of sites within two vulnerable lowland populations (Pembrokeshire and Severn Valley), through landscape scale enhancements and local improvements to habitat.
- Maintain the population at Potter Heigham.
- Introduce L natans to at least two new sites in the Norfolk Broads by 2012 (if preparatory research shows this to be feasible and desirable).
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(This guidance is a general summary; for more detailed information or advice, please consult the references or contacts below.)
This plant is an opportunist, growing best in open water conditions. It has been described as “a prolific opportunist” in the wake of a severe disturbance by dredging or other clearing operations. However, it is unable to compete once the ditch becomes overgrown.
L. natans requires clean water and high levels of light. Management should therefore aim to retain ditches in a fairly open condition, without removing the plant altogether during works. Dykes should be cleared three-quarters of the way across, every two to three years. Work should be carried out from different sides each time. An NE (Defra development) licence is required.
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2 Gilders Way
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Barrat-Segretain, M.H., Bornette, G., & Hering-Vilas-Boas, A. (1998). Comparative abilities of vegetative regeneration among aquatic plants growing in disturbed habitats. Aquatic Botany 60: 201-211.
Bazydlo, E. (2004). Effect of environmental conditions on the populations of Luronium natans (L.) Raf. Polish Journal of Ecology 52 (2): 181-189.
Bazydlo, E. and Szmeja, J. (2004). Effect of pH, dissolved organic carbon and total phosphorus concentrations on selected life history traits of Luronium natans (L.) Raf. Polish Journal of Ecology 52 (2) :191-200.
Beckett, G., Bull, A. and Stevenson, R. (1999). A Flora of Norfolk. Norwich: Jarrold Book Printing.
Charlton, W.A. (1999). Studies in the Alismataceae. X. Floral organogenesis in Luronium natans (L.) Raf. Can.J.Bot. 77:1560-1568.
Greulich, S., and Bornette, G. (1999). Competitive abilities and related strategies in four aquatic plant species from an intermediately disturbed habitat. Freshwater Biology 41: 493-506.
Greulich, S., Bornette, G. and Amoros, C. (2000). Persistence of a rare aquatic species along gradients of disturbance and sediment richness. Journal of Vegetation Science 11: 415-424.
Greulich, S., Bornette, G., Amoros, C. and Roelofs, J.G.M. (2000). Investigation on the fundamental niche of a rare species: an experiment on establishment of Luronium natans. Aquatic Botany 66: 209-224.
Kay, Q.O.N., John, R.F. and Jones, R.A. (1999). Biology, genetic variation and conservation of Luronium natans (L.) Raf. in Britain and Ireland. Watsonia 22: 301-315.
Lansdown, R.V. and Wade, P.M. (2003). Ecology of the Floating Water-plantain, Luronium natans. Conserving Natura 2000 Rivers Ecology Series No.9. Peterborough: English Nature.
Lockton, A. (2008). Luronium natans update. Unpublished report to the National L. natans Steering Group.
Maessen, M., Roelofs,J.G.M., Bellemakers, M.J.S. and Verheggen, G.M. (1992). The effects of aluminium, aluminium/calcium ratios and pH on aquatic plants from poorly buffered environments. Aquatic Botany 43:115-127.
Nielsen, U.N., Riis, T., and Brix, H. (2006). The importance of vegetative and sexual dispersal of Luronium natans. Aquatic Botany 84: 165-170.
Nielsen, U.N., Riis, T. and Brix, H. (2006).The effect of weed cutting on Luronium natans, Aquatic Conservation: Marine and Freshwater Ecosystems 16: 409-417.
Rich, T.C.G., Kay, G.M., & Kirschner, J. (1995). "Floating-water plantain Luronium natans (L.) Raf. (Alismataceae) present in Ireland", Ir.Nat.J. 25, 4: 140-145.
Smits, A.J.M., Kleukers, R.M.J.C., Kok, C.J. and van der Velde, G. (1990). Alcohol dehydrogenase isozymes in the roots of some nymphaeid and isoetid macrophytes. Adaptations to hypoxic sediment conditions? Aquatic Botany 38:19-27.
Smits, A.J.M., Laan, P., Thier, R.H. and van der Velde, G. (1990). Root aerenchyma,oxygen leakage patterns and alcoholic fermentation ability of the roots of some nymphaeid and isoetid macrophytes in relation to the sediment type of their habitat. Aquatic Botany 38: 3-17.
Willby, N., Eaton, J., and Clarke, S. (2003). Monitoring the Floating Water-plantain. Conserving Natura 2000 Rivers Monitoring Series No.11. Peterborough: English Nature.
Willby, N. and Eaton, J.W. (1993). The Distribution, Ecology, and Conservation of Luronium natans (L.) Raf. in Britain. J. Aquat. Plant Manage 31: 70-76.
Botanical Society of the British Isles: www.bsbi.org
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