Cornish Hedge

When I first moved to Cornwall, it took me a while to understand Cornish hedges - I am neither Cornish nor even British and a hedge for me was a kind of trimmed bush. A Cornish hedge, from what I now understand, is a wall made of stones with a space in the middle filled with earth. Things grow out of it, making it unrecognizable as either a wall or a hedge.
In the spring they are rife with wild flowers (like this one) until they are trimmed - usually mid-summer.
I just read there are more than 30,000 miles of such hedges in Cornwall today - 3/4 of which are ancient. More information here.