Image: L. Rooney
The maps at the end show distribution of Giant Horsetail in Kent. I suspect that Lliam has been using Quentin's helpful video, showing how to make a customised distribution map for any species in your vice-county. But if you want to see national distribution of Giant Horsetail - or any other plant recorded in Britain or Ireland - you need to go here for our tetrad maps, here for our hectad maps and here for the Big Database.
And when you're ready for some advanced Equisetum ID, try the Plant Crib pages.