Then don't you think it is up to "US"as the new guardians of the stones to do something about it? All it takes is a pair of secuteers and a can of weedkiller that goes to the roots. It's not rocket science I personely do not like useing weedkiller but sometimes it's the only option, rather that than getting ripped to shreads trying to pull the dam things out.
Snap

Dare I say I think the brambly version looks best?
Sometimes "unkempt and antique" adds charm.

Call it the Ozymandias effect.
;)