If you have hedge apple trees (also called Osage Orange), you know about the long, sharp thorns. It makes sense that it was once used as natural fencing – who or what would dare push through that? Having tangled with it more than once, I keep this particular tree pruned back so that none of the spines are at eye level (!), yet leave enough branches to create an aerial predator-unfriendly shelter for the fowl (though those thorns can also get stuck in their feet and result in bumblefoot). I consider this a truce of sorts, being extremely loath to cut down any trees.
For those who like to look for hidden meanings in poetry – as I do – perhaps this poem could also be metaphorical. Who knows?