By Adrian Dyer and Alison Evans
This identification key covers the most common and widespread fern species native to Britain and Ireland. There are in addition some very rare species that are unlikely to be found by any but the most committed fern hunters. These are listed in the Appendix
Further details for identifying all these species are given in Merryweather (2020), Hutchinson and Thomas (1996); Page (1997); and Merryweather (2005, 2007). Assistance with the more difficult identifications may be obtained from The Plant Crib (Rich, T.C.G and Jermy, A.C., 1998, published by BSBI) which is available on-line.
Although now recognised as the closest relatives of ferns, all horsetails have been omitted from this key. Most published identification aids include the 8 horsetail species and their several hybrids, but their structure, and their diagnostic characters, are very different from ferns and beginners are advised to take one step at a time and become familiar with one group before tackling the other.
Hutchinson, G. and Thomas, B. A. (1996) Welsh ferns. National Museums and galleries of Wales, Cardiff.
Jermy, C. and Camus, J. (1991) The Illustrated Field Guide to Ferns and Allied Plants of the British Isles. Natural History Museum, London.
Merryweather, J. (2005) Key to Common ferns. Field Studies Council,Shrewsbury.
Merryweather, J. (2007a) The Fern Guide. Field Studies Council, Shrewsbury.
Merryweather, J. (2020) Britain’s Ferns, Clubmosses, Quillworts, and Horsetails. A field guide. Princeton WILDguides. ISBN 9780691180397
Page, C. N. (1997) The Ferns of Britain and Ireland. Second Edition. CUP, Cambridge.
The 9 rare native British and Irish species are restricted to very few sites and in some cases to very few individuals
The 6 scarce native species are absent from most of Britain and Ireland, and confined to a limited habitat range, but may be locally common within their restricted distribution