When you’ve walked a mile or two up a limestone gorge to see a ‘very special plant’, you are ready to be impressed, so I have to confess that the sight of a large fern growing on a cliff face on the other side of the gorge did not really fill me with awe. Back home, I did a bit of research and found that it is indeed an interesting fern that spreads by rooting from the tips of its fronds. Should you wish to grow one (I might resist) it gets very large, is tender in this country and is available from Architectural Plants.