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NEYEDC improve and inform environmental decision making, conservation, land management and sustainable development in North and East Yorkshire through the collation, management, analysis and dissemination of biodiversity information.

The Natural History of Yorkshire in 100 Species

Explore the rich and diverse natural history of our region through the stories of 100 species, told by the people who know them best.

#35 Pillwort by Anne Carter

Meet Anne Carter, Northern Project Officer for the Freshwater Habitats Trust!

Anne has an interest in all things pond-y and is a huge fan of amphibians (Palmate Newts are her favourite!). However, she is also particularly keen on championing the rare pond critters that folk usually forget about, include Pond Mud Snail and Medicinal Leech. You can contact Anne via email at acarter@freshwaterhabitats.org.uk, find out more about the Freshwater Habitats Trust on their website, or follow them on Twitter @Freshwaterhabs. You can also follow Anne on Twitter at @annefreshwater.

Anne’s chosen species is the UK’s only native aquatic fern, Pillwort (Pilularia globulifera). Pillwort is a very distinctive little grass-like plant. It is in fact an aquatic fern with thin, thread like leaves which unfurl from tight coils as it grows. It has hard spore cases, ‘the pills’, at the base of the stems. In the right conditions it forms a creeping mat over bare mud at the margins of ponds and lakes which makes it look like a miniature bright green lawn.

Pillwort (Anne Carter).

Pillwort is a specialist of these bare pond edge habitats - it is not a good competitor and only thrives where there are few other plants. It requires seasonally fluctuating water levels and favours temporary and bare open margins. These are often created by the gentle poaching and grazing of livestock, so suitable management is also key to its ability to take hold in an area. The plant also favours slightly acidic ponds on clays, sands and peaty substrates, and is most often found in open habitats including heathland and acid grassland. Occasionally it can be found in larger ponds and lakes, particularly sand and gravel pits, but only where fluctuating water levels and suitable management occur. You can find out more about Pillwort on the NBN Atlas.

Unfortunately, Pillwort is declining rapidly throughout its north-west European range and the UK now holds a substantial proportion of the global population. Historically it occurred in about 250 ten kilometre squares in the UK, but is now restricted to just a handful of scattered locations, including in Yorkshire, Freshwater Habitats Trust’s Flagship Pond sites at Foxglove Covert, Skipwith National Nature Reserve and Strensall Military Training Area. Previously, North Yorkshire was a stronghold for this species, but a mixture of aquatic pollution and loss or change in management has led to its decline.

Carpet of Pillwort at Skipwith NNR (Anne Carter).

Pillwort was once abundant at Skipwith, with a good population present on ‘Pillwort Pond’. But by 2015 none could be found and it was thought to have been lost from the reserve altogether. However, in 2017, during Freshwater Habitats Trusts’ ‘People, Ponds & Water’ (PPW) project, a population was discovered on Horseshoe Pond. The PPW project was a national partnership project that worked with volunteers across the country to monitor, manage, and protect freshwater wildlife. The discovery of this population kick-started the ‘Yorkshire Pillwort Project’ and in 2018 surveys were carried with the invaluable help of Dr Barry Wright of the Yorkshire Fern Group and local volunteers. The population on Horseshoe Pond was doing well, but surveys of surrounding suitable ponds did not come up with any new populations. In order to secure and strengthen one of the few remaining sites for this rare fern in the Yorkshire lowlands, a programme of translocations began.

Monitoring Pillwort using blank CD’s and drone footage (Barry Wright).

In 2019, Pillwort was translocated into a group of new small shallow ponds, created with Pillwort in mind as part of the PPW project. These were named the Runway Pond cluster, as they were created on the site of an old airfield which had been reclaimed for nature. New technology was also tried out in the form of Barry’s drone camera to help with future monitoring. By using blank CD’s to mark the extent of the Pillwort carpet, and then taking an aerial photograph using the drone, it is possible to compare populations from year to year – a great example of simple but effective monitoring methods. Monitoring has continued at Skipwith into 2020 and 2021, and so far the Pillwort is doing well with the translocated population expanding and new populations also discovered on other ponds on the site!

Recording & monitoring

There are no specific recording schemes for Pillwort, but if you do come across any, please email Anne on acarter@freshwaterhabitats.org.uk.

Further information and acknowledgements

NEYEDC would like to thank Anne for her time and expertise in helping to create this blog.

NEYEDC