|Scope: Global & Europe|
|Scientific Name:||Pilularia globulifera L.|
|Taxonomic Source(s):||Christenhusz, M. and Raab-Straube, E. von. 2013. Polypodiopsida. Euro+Med Plantbase - the information resource for Euro-Mediterranean plant diversity. (Accessed: 2015).|
There are no significant taxonomic issues associated with this name.
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Christenhusz, M., Lansdown, R.V., Bento Elias, R., Dyer, R., Ivanenko, Y., Rouhan, G., Rumsey, F. & Väre, H.|
|Reviewer(s):||García, M. & Schaefer, H.|
Global and European regional assessment: Least Concern (LC)
EU 28 regional assessment: Least Concern (LC)
In spite of the decreasing population trend and its decline in habitat extent and quality, this rare species is assessed as Least Concern since it has a large distribution area, it is resilient and can remain in the spore bank in the soil for many decades, and it is unlikely to qualify under any of the threatened categories. Further research and monitoring are needed on its existing subpopulations and their habitats.
|Previously published Red List assessments:|
|Range Description:||Pilularia globulifera is endemic to Europe, where it mostly has a western distribution, occurring in southern Scandinavia, the United Kingdom and Ireland, the Netherlands, Belgium, Germany and Poland, extending through France to the west of the Iberian Peninsula and southwards through the Alps to Italy and Croatia. Its area of occupancy (AOO) is 3,120 km².|
Native:Belgium; Croatia; Czech Republic; Denmark; Finland; France (France (mainland)); Germany; Guernsey; Ireland; Italy (Italy (mainland)); Jersey; Luxembourg; Netherlands; Norway; Poland; Portugal (Portugal (mainland)); Slovenia; Spain (Spain (mainland)); Sweden; Switzerland; United Kingdom (Great Britain, Northern Ireland)
|Range Map:||Click here to open the map viewer and explore range.|
Most information suggests that subpopulations throughout its range are declining, although it must be noted that this species is often overlooked, and it has re-appeared from the natural spore bank when canalised rivers were restructured along their original water courses, for instance in the eastern Netherlands (M. Christenhusz pers. comm. 2016). The Pillwort typically occurs as dynamic metapopulations due to its habitat requirements and that in almost all cases detailed searches have discovered new subpopulations, or subpopulations that were believed to be lost were found again. The overall population trend is decreasing, and these declines happened mostly in the last 50 years.
|Current Population Trend:||Decreasing|
|Habitat and Ecology:||Pilularia globulifera typically occupies bare gravel, silt or muddy flats on the margins of fresh-water lakes, ponds and temporary (vernal) pools, fens, ditches, tracks, etc., usually in areas where fluctuating water levels suppress competition from taller plants. It also grows on silty mud at the edges of slow-flowing river backwaters and river mouths, in wet sandy hollows in dunes and heaths, and sometimes invades muddy ditches and old claypits in shallow, wet situations. It will survive permanently submerged, but only produces spores where the water level drops in the summer (Komarov 1968, Page 1997). It occurs at elevations between 0-380 m.|
|Use and Trade:||Pilularia globulifera is increasingly sold for garden ponds (propagated from cultivated stock), particularly in the Netherlands and the United Kingdom, but it is not clear whether this trade affects wild subpopulations. It does not seem to be harvested from the wild, and naturalisation events are likely to be rare.|
|Major Threat(s):||The main threats to Pilularia globulifera are the stabilisation of water levels and the drainage of temporary wetlands. It is possible that even low-level eutrophication may pose a threat to the species, since it enables colonisation of otherwise unsuitable habitat by more aggressive plants, outcompeting the Pillwort. Invasive macrophytes such as Crassula helmsii pose another serious threat to this plant.|
Even though Pilularia globulifera is widespread and can occur in abundance in suitable habitats, it is listed as threatened in nearly all countries in which it occurs:
|Citation:||Christenhusz, M., Lansdown, R.V., Bento Elias, R., Dyer, R., Ivanenko, Y., Rouhan, G., Rumsey, F. & Väre, H. 2017. Pilularia globulifera. The IUCN Red List of Threatened Species 2017: e.T167887A85436052.Downloaded on 21 September 2018.|
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