Printed

Britain’s Ferns: A field guide to the clubmosses, horsetails and ferns of Great Britain and Ireland by James Merryweather (Princeton Wild Guides, 2020)

Common Ferns  by Merryweather & Roberts (Field Studies Council, Wild ID fold-out card, 2005)

Websites

Google Lens: Go to google.com and there is a camera icon at the right of the search bar. Click on this, and you can drag and drop any image and it will do its best to identify it – so can be used for any flora and fauna, vertebrates and invertebrates etc. (as well as buildings, landscapes – anything, in fact.)  Worth a look, but treat identifications with caution!

Apps