#30 Moonwort by Barry Wright

Meet Dr Barry Wright, Chairman of the Yorkshire Fern Group!

Part of the British Pteridological Society, the Yorkshire Fern Group studies ferns in the county of Yorkshire, with some excursions into neighbouring counties, particularly Cumbria, Durham, and Derbyshire. In 2021 Barry, along with other members, formed the society's Fern Monitoring Group (FMG) to develop methods to monitor and record some of our fern flora, in particular rarer species that may be on the limit of their distribution in the UK and species that might be considered as indicators of the 'health' of our environment going forward into the predicted climate crisis. Barry has had a keen interest in ferns since the early 1970s when he was given an Adiantum house plant fern to look after by the curator of the botanic gardens of Hull University, where he studied Zoology. You can contact Barry via email at Yorkshire@eBPS.org.uk or FernMonitoring@eBPS.org.uk.

Moonwort with young fertile frond (this will become taller before shedding spores).

Barry’s chosen species is Moonwort, Botrychium lunaria. A primitive fern species, it looks nothing like what most people would call a fern. It is small (<10cm), but occasionally 15cm. It is also unlike many ferns people will be familiar with in that it grows in the open in grasslands, usually unimproved short turf swards. Its main stronghold is in upland areas and, as a guide, seems to be more common above 300m on moor tops that are typically sheep grazed grass and amongst heather. You can find pictures of this species on iNaturalist. It can grow at altitudes up to 2000m on the continent and elsewhere, but can be found at sea level in other areas. It has a slight preference for more alkaline soils that are relatively dry. Each growing point, or crown, has a maximum of two fronds per year, one sterile and usually, one fertile, with spore-bearing sporangia arranged like a small bunch of grapes, hence its common name in the US of 'grape fern'. Although it produces spores, its main method of colonisation and propagation is by underground rhizomes that radiate out during the year from the current year's node or crown to end at next year's crown point. It comes up in different places each year depending on how many rhizomes the main crown produces and how far they can grow during the summer before ending in the resting bud for next year. You can find out more about Moonwort on the NBN atlas.

Moonwort is an uncommon species of ancient and unimproved grassland and is important as a component in these swards, and as an indicator of environmental health. Unimproved grassland is a threatened community that can easily be damaged or destroyed, and therefore retaining such habitats is important for maintaining populations of Moonwort. It is an uncommon plant both in Yorkshire and nationally - the BSBI atlas reports a slight negative change in index (-0.43) suggesting unimproved pastures may still be under threat and are becoming improved or re-seeded.

In Yorkshire it is also associated with grasslands covering disused lead mining spoil heaps, a link to the region’s industrial history. Moonwort also has a significant cultural history owing to its unusual morphology. The shape of the sterile frond resembles a key and it is reputed to be able to undo shackles and locks. It is also supposed to remove horses' shoes if they should tread on a Moonwort plant. Even more bizarrely, the individual frondlets are supposed to be used as saddles by fairy folk for use on their suitably sized miniature horses! It is the resemblance of the moon-like and crescent-shaped frondlets that gave rise to the name Moonwort. Barry notes one of the reasons he loves Moonwort is that it and other similar species, such as Adder’s-tongue, are unloved species, being small and un-fern-like. Someone has to stick up for them!

Monitoring

Moonwort has proved difficult to survey reliably and in a repeatable manner. Barry and the Yorkshire Fern Group first started looking at Moonwort in 2001, during the foot and mouth outbreak. During this period, it was forbidden to walk on areas that were not hard surfaced. In the previous year, Barry had noted when doing some work in the North York Moors National Park that every time he stopped to change into his boots he noticed small Moonwort plants in the short turf on the roadside verges. As these locations were all adjacent to tarmac roads the opportunity arose for doing field work during the foot and mouth outbreak without straying from any hard surfaces.

In the beginning a request was made to the National Park authority for their records of Moonwort in Yorkshire. This returned only six records. This suggested that the species may be rare in the county. However, the Yorkshire Fern Group surveys overturned this in a dramatic way. They systematically walked many of the roads in the North York Moors that were above the 300m contour. Some of the roads were devoid of Moonwort, as far as they could determine. However, some roads were rich in the species and there were small patches to extensive colonies extending for several kilometres on both sides on some roads. Each colony was GPSed and plotted and they increased the records to several thousand just in the first couple of years.

Typical quadrat showing 10cm grid, metal detector and GPS (R), and Scale Bear (10cm tall sat down) in cell A4 looking at cocktail-sticked Moonwort in cell A3.

A typical quadrat with each frond plotted - 2013 (survey year E) quadrat 236 (note outlying cluster and core area).

After surveying a large number of roads and sites in Yorkshire, they decided to continue their surveys into monitoring, which began in 2009 and has continued every year since. At present they have adopted fixed 1m x 1m quadrats on a particular section of roadside on the road from Grinton to Redmire in the Dales. Alarmingly, aside from a few ups and downs in the early years, there has been a steady and dramatic decline in every quadrat. With over 200 plants identified between 2010 and 2013, from then onwards numbers have almost consistently dropped. In 2020, only two plants were found.

Moonwort is likely to be uncommon for a variety of reasons. Firstly, it is thought to be under-recorded because of the narrow survey window on sheep-grazed turfs; there is likely to be a single frond ‘flush’ and, once completed, no further fronds are produced that season. This was established using the team’s fixed quadrat surveying method. These surveys also need to be early in the year, before many botanists are out in the field. Because of its morphology, inexperienced surveyors may also miss the plants when they are very small and in low numbers. Additionally, unimproved grassland is still under threat, with continued re-seeding of swards and improvements using fertilisers and herbicides. Lastly, Moonwort may simply be an uncommon species!

Further information and acknowledgements

More about fern monitoring can be found on the British Pteriodological Society website.

NEYEDC would like to thank Barry for his time and expertise in helping to create this blog.